Just a note: 98s 70 series are available with 5 speed and the
turbo engine (and power was even bumped up a bit in 98).

Apparently, that configuration (manual 5spd + turbo) was sold in Canada. You might get a used up there but importing it may be difficult because of emissions issue. As owner of a 5spd non-turbo wagon myself, I dream of having one under the hood - like that VW Jetta 1.8T ...

yt855
1994 5spd non-turbo 855 at 96k miles

The turbo engine has different pistons, sodium filled valves,
oil cooled crank, lots of check valves, smaller displacement
engine (for thicker cylinder walls to handle the heat), lower
compression, different ECU, different exhaust, coolant routing
to get coolant to the turbo and back to the engine, ditto for oil,
and many other mods. The premium they charge for the turbo when new
is really a good deal -- it is well engineered and much more then
a bolt-on to the normally aspirated engine.

When this question comes up (every few weeks) the general reply is
that it is cheaper to just find a turbo. Or, for those that own
the car already, it is cheaper to sell it and but a turbo model.

It would be real expensive,even using used parts.Difficult?You will need a turbo ECM,intercooler,all of the charge air pipes,you will have to drill the intermediate section of the engine block for the turbo oil return pipe.You will have to drill and tap the block for an oil pressure banjo fitting to provide oil pressure to the turbo.I cant remember if the wiring harness is the same,and Im sure I have forgotten something.