Mopar #'s Matching

Long time Mopar fan and previous member to this forum. I am just getting back into it now because I have the option to purchase two 1965 Barracudas. The motors are out of them already from previous owner and I believe 1 was a 273 Commando car. Did Mopar do #'s matching with car and engine in 1965? I am just wondering if I should put back in the original 273 (not sure it actually is) to keep original or should I go with a 318/340 right off the bat if I am looking to build the engine up down the road? Not looking to do anything crazy with power, but just don't want to get my butt handed to me by my Dad's '64 Barracuda that has a 318.

Any suggestions/feedback would be greatly appreciated!
It will cost the same to build a 340 as 273 and not limited by early heads/intake bolt. Schumaker makes a kit with motor mts/ insulators/bolts to make the change- I have a set NIB I can sell for $100- check there website for now price-