I don't know anything about your 242 so can't make any recommendations,
nor have I seen any of the other cars.
If the 164 is in relatively good shape and its ONLY major problem is
the carburetors, I would jump at it.

I have a 73 145, in generally good shape, but since I have 4 cars and
there are only two of us, once I get it in driveable condition I will probably
get rid of it one way or another. (It will probably stay in the family.)

The 145 and the 245 have essentially the same body shell and safety
features, same cargo capacity, etc. Given the choice between them in
equal condition (which is purely a hypothetical situation, since no
two cars are ever truly equal) I would prefer the 145 because I am very
familiar with their engines, powertrain and suspension, and I have nearly
a ton of spare parts for them. But if you are more experienced on the
240s maybe they are a better car for you. I don't know you at all so I
can't say. In general the B20 has more accessible parts than the B21
and following engines because the B20 sits up straight and you can pretty
much get to both sides of it. It is a little smaller (130 cc) but can
be bored bigger and power substantially enhanced by other means, with which
I am sure you are familiar if you follow this board.

I'm not telling you to do anything. You gotta make up your own mind!
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma