Any small block V-8 or later inline 6 would be a good choice. Nothing from the 235 can be used on either of these engines.
Crate 350's go for about $1700 plus you would need an intake manifold, carb, air cleaner, distributor, exhaust manifolds & exhaust system, pulleys, throttle linkage, flex plate, and other related components & accessories. Add another $1000 for components.
Keep in mind that you likely have a 3:90 rear end and probably won't get great mileage with the 350 trans. A 700R4 or 2004R OD trans would be a better choice.
Fred

Last edited by rfs56trk; 10/21/2011 5:19 PM.

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine