68 Sport Fury

I have a 68 sport fury that needs a lot of work. It has a 318 and and auto(not sure which one). I put in a new distributor, wires, plugs, and rebuilt the carb. It has low compression in some of the cylinders. The trans was rebuit before i bought it. I was wondering if it would be more cost effective to swap out a big block or rebuild the small block. The 318 is a 2 barrel, so if i was to put a 4barrel manifold i would have to either put on new heads or portmatch them to the manifold. If i was to put in a big block, i know that i would have to get new motor mounts, but is there anything else that i would have to swap? Its a huge car so i dont think that i will have any clearance problems whatsoever.

Thanks
Logan

big blocks will fit the body no problem, you will need, besides motor mounts, radiator, transmission, maybe rearend depensing on whats in there, may need stiffer torsion bars, four barrel on a 318 works fine, they were available a few years

thanks for your info. I think i'm gunna go with a big block. I found one that is built up and only has 9k miles on the rebuild for 800 bucks and a rebuilt 727 for 300. Thanks again.
Logan