If it were me I woundn't put any more money into the 305. Save up for a 350 or 383 or something along those lines. I would also go with a carbureted setup rather than staying with TBI. The cheapest thing to do would be to find an old 350 truck engine, scrap everything but the block and build it how you want it. I would go with an eagle crank and rods, SRP pistons, a good comp cams hydraulic roller cam, 1.65:1 roller rockers, a good set of 2.02/1.60 heads, a edelbrock performer RPM intake mani (or just go with a tunnel ram!!), a good holley carb (750cfm or so), a set of hooker long tubes, and a 3" dual exhaust setup should make you somewhere between 350-500hp depending on the cam, pistons, and heads you go with. The small block chevy engine is the absolute cheapest engine in the world to build. Hell I wish I had another project with a sb chevy.