<VV> Engine identification

[Hugo Miller]

I seem to have accumulated four 1964 Corvair convertibles, two of which 
are running and road legal, and I have been running these two as daily 
drivers for a couple of years, but not done any serious work on them 
yet.
  I am about to start properly restoring the one with the best bodyshell 
(it's from Arizona or Nevada & is totally rust-free), but it has the 
worst engine. I'm looking to do a 'mix & match' with one of the other 
cars, i.e. probably swap the entire drive-train over. Or is it easier to 
just swap the engine?
My question is how can I identify the engine size and type on each car 
so I can make a comparison? I have three with 2 speed PG and one 4 speed 
manual, and I haven't even decided which transmission option to go for 
yet.
Any input gratefully received.