The easiest would be a Clevland with a carb, all parts would fit as from the factory. However you would not be the first to put the 32 valve motor in. I belive you are correct in the fact that tuning and fuel injection are a plus with a modern engine. I don't know about mounts and even if the moduler engine will even bolt to the ZF without some adapter. This forum can be of great help there. If I had to start with nothing like you. I'd go with the new stuff and end up with a car that gets better than 11 mpg @ $2.38 PG
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