318/340 questions please help!!

Sounds good, I have an Eagle crank, cast, stock floating rods, and Ross pistons..... Unlike some, I never see a reason the not use the stock light 318 floater rods until I am spinning up over 6K, and with the 318 being a small bore, the piston is lighter than say, a 4" or 4.04... The 390 will make more power than a 348 stroker, but it is, in the end, what YOU want to do. A 348 will obviously have the ability to rev higher.

My only reason for going 390, would be because of the small bore/valve shrouding, you have more time when the piston is moving, to suck and push. LOL It's your call, do some reasearch, and make your decision. After all, even if you decided to go 273, it is YOUR car, and there is no wrong answers... :)