Advice needed: Budget rebuild

You dont need exotic parts... You have a good base with the engine you have. My plan would be this..Rebuild the engine properly, with a couple of mods..First, use KB pistons, no need for forged heavy slugs..Bore, hone, and deck the block, resize the rods with good bolts (i use ARPs), trun the crank if needed, and internally balance it. For heads, I'd sell the Js you have, but put the $$ into a set of "302" castings..those are 86-91 truck 318 swirl port heads..Great for street motors. Have the heads redone with 1.88/1.60 vavles, and a performance valve job..As a bonus, the exh seats are hardened for unleaded use, and the chambers are closed for good detonation resistance (good quench). with good parts, cam, timing set, valve springs to match the cam, teflon seals, the works, you can be done for $2500..You will need to have the intake ports enlarged to match the 340 intake, but you can use that..This build will run on pump gas, and will embarass many a larger engine in an A body chassis. a conservative 300 hp is easy, and even better, lots of usable torque.