Parts exchange between a 18hp 57 Rude & 18hp 64 Johnson?

[BloodStone]

Hello gang;
I just recently received a 18 hp 1957 Evinrude Fastwin manual start with pressurized fuel tanks (good shape) & a 1964 Johnson 18 hp with electric start & standard tanks (fair shape) What I want to know is, how many of the parts are interchangeable between the two? Specifically I'm talking, electric starter, gear shifter, flywheel, & fuel system conversion (complete).
To be precise, taking these aforementioned parts from the 64 over to the 57, etc..?
Final question, if both motors ran equally well (compression test confirms both are in fine shape that way), which would you keep & which one would you sell & briefly why?
Thanks

 

[Andy]

If it were me, I'd keep one and give one to that guy Andy. He's a pretty nice guy..
Seriously though, why not keep them both? That way you can have one for a spare.