possible 318 build

If the shortblock and 596 heads are actually in decent shape use them, I've thrown together similar stuff and it has ran fine.

The key to making it work is a 3.91-4.30 gear and higher stall converter, you don't need a $800 PTC 9.5" for this setup, a daaco 2500 stall will work fine, they're available from most supply houses.

For a cam I would run something small like the large summit cam or the MP 268/272 and get a set of $80 comp springs, the stock rockers will work as long as they're not worn out, you will need headers and a 600-650cfm carb and you will need to re-curve a stock dist so you have 15-20* at idle, 36-38* total.

You need to check the engine over really good while it's apart, make sure the bores don't have a bunch of taper and that the valves are sealing, you don't want what little compression it has going past the rings or out the exhaust port. I put one of these together for my old Duster and everyone that's seen it run or ridden in it thinks its a 340 or 360, I ran some 8.60's in the 1/8 in driver trim on regular radials.