Not all 305 heads are bad, most 305s do not suffer flow problems until 6.5k rpms. There are several types of 305 heads, with the TBI swirl port heads having very poor flow and not normally found on carbed 305s used in g bodies. People tend to forget 305s have smaller cylinders which are easier to fill and do not require as much flow as a 350 which has a harder time filling its larger cylinders. It is also why 305s can run more compression than a 350 without spark knocking. There are quite a few LO 350s that do not even make LG4 level power out there such as 70s smoggers and the cheap crate motors that barely make 200 hp, not a good upgrade for the money and effort.
Now one important piece of info Luke left out is the year of his LG4. Early ones had 8.5 cr while later ones were upgraded to 9 cr. Aftermarket carbs are a waste of money for a street cruiser. I agree a roller cam swap/ conversion is overkill on an engine you are not going to keep. Since the op has a overdrive trans, he should go with a 3.73 ratio rear axle with 28 spines out of a later MCSS. Swapping the whole rear axle is easier and cheaper than changing the gears which requires expensive tools.
They were done on the cheap, zz4 intake was $20 used, headers were $170 used, both engine and trans were $250 combined. The posi rear was $100. Most expensive part was having the carb rebuilt right, back then I did not know Qjets as much as I do now. The new performance cam was $150. My Regal was originally a base V6, which is a real dog, stuck at 110 hp without rebuilding the entire engine to better specs. My car makes more than double that now, so I am happy.
