Hi,

That is a very good question, that I have no experience in!
With that said, I’m just going to babble my little head off! ((:))

My first thought is a “big No,” but that doesn’t mean anything.
Most people, like the manufacturers, would make or throw in a bigger engine and wouldn’t mess with it. It doesn’t behoof-them too!
This depends on their prototype research/marketing budgets and the production inventory-contracts.
Easier to zero-in to make another complete model.
Volvo didn’t operate on a two year turn-over like other car makers so I’m back to a MAYBE.

In the following years of Later B230 engines, as a whole they had many changes done internally as far as the moving parts are concern.
This was because they are “hopping up” the engine products all across the board. They cheated on the race circuit, right under the hoods, lots of times!
There was a little racing blood in the veins of the 140 designers and it stayed through the 240 years too! Lots of other car manufacturers were trying to build up sales then. Volvo even advertised about blowing doors off V-8 equipped cars. I never saw it happen, just heard the blabbing mouth!

There is another block that fits in between the B21 over to the B230’s and it’s called a B23. It was an intermediary block and head change out experiment to be supporting of turbos or even supercharger advancement in Europe. Heads and cams shapes galore!

The B21 block just seems to be a more narrow and smaller block in width to me, but that’s only a feeling, as I have no other proof!

If there is any the spread of head bolt pattern, that would be a killer.
Those have to be matching up along with the location of oil pressure, drain back holes and the coolant passages.

The B21 head might have slightly smaller passages but would be irrelevant in your case, since the larger displacement of the engine will not be getting the fuel to burn.
The last two could be a concern with the increase two hundred cubic centimeters of displacement and a turbo being able to create more heat. You are not going that route.
Interesting enough to note though, is the thermostat and outlet pipe is the same throughout all of the displacements. Go figure?
A standard calculation probably was used with a fudge factor already in it as in being “over built,” for the worse case scenarios.
I feel that it was not much of a concern on daily drivers of non turbo or even turbos, because there a “clause or disclaimer” in “all warranties” about “racing” production made vehicles.
Even when you buy a Corvette new!
It doesn’t appear that much was done to the original castings, if you gage the overall look, of all the red blocks!

You are right to think that the injectors have their slight differences but they are basically in the same place and angle aren’t they?
I would wonder more, if a B230 head could be modified to accept the CIS injector bodies.
As I remember, the injector itself is quite thin or is very similar to the electronic injectors diameter, but only have larger upper bodies, up higher, for the electric coils.
You know that the B21 head utilizes a phenolic holder. The idea was to isolate it from heat of the head.
You can see, later on, those things went bye bye as not being needed starting with the B23 LH’s, in or around 1984.
Something to “ponder” about fitting up the CIS into a B230 head?
You might want rethink things into making your holders of the CIS system, fit into a B230 head.
That head, that “righteously” fits the B230 block!
The B230 block and those heads are going to be lot more plentiful, as time goes on, if not already.

I know you realize that the B230 block is going to have a B21’s head breathing capabilities by staying with this idea?
The mixture controller of the CIS will see the more air flow from a slower physical moving engine at idle.
Does the 1976 have a LambdaSond oxygen sensor?
Is it going to self tune like the 1978 GT’s had on their B21?
Yes, the engine block is capable moving more air but as a normal daily driving performance requirements come up, it’s going to make the same B21 power with more or less torque being noticeable.
I don’t know that the mixture will be that much leaner for any reason except on a cold startup? The mass of the engine and the air flow may be slightly leaner then.

I imagine the Various B230 blocks have pistons with different part numbers. For sure with minority a diameter changes or complete design changing all by itself.
I think the B23 to B230 block had a stroke changes with the crankshaft rods and journal width movements.
It’s a lot easier to get more displacement with a Length of stroke change. You change torque and rev-up characteristics too!
The distance from the top of the piston to the wrist pin center can be adjusted along the way with its diameter those numbers changing along the way.
If the top of pistons themselves stayed the same in regards to the “deck of the block” and could give way to a possibility of this area working out.

This sure was a lot to think about and babble about! Whew?
I hope I made some sense of it and you can tell us what you find by measuring things out, carefully!

Phil