Quote:

I question the widely held belief that the 273 vs a 318 or 340 is a higher revving motor, which I think you maybe implied, I think the contrary would be more accurate.



I can see it side to side against stock 4 bbl versions of each. I don't know about exact piston weights, but assuming similar casting material the smaller 273 bore should be a lighter piston, also IIRC the 273 had a lighter rod that is still sought after, early ones also had solid cams so no hydraulic lifter rpm limit. Lighter rotating assembly, higher rpm potential and faster acceleration of the engine internals.

Again this assuming comparison against a stock 4 bbl version of each LA engine.

That said, I stand by my previous statement about a late 318 being a better/cheaper choices for the OP, considering his 273 is not complete and not a 4bbl package for a starting place.

I picked up a complete roller 360 in a yard do $250. A running 318 could probably be found for less. Used eddy performer or weiand stealth intake to match the 302 ports, 100 bucks maybe? Regrind the factory roller cam to a performance grind $200? haven't priced regrinding. Gaskets, bearings, rings, 4bbl carb for either about the same price and should be replaced in either motor anyway.

If OP was doing a resto then sure build the 273. It doesn't seem like originality is a goal, so the upgrade is a no brainer to me.

"The happiness of your life depends upon the quality of
your thoughts" ~ Roman Emperor Marcus Aurelius