well, as most people would say, your cheapest power comes from compression, theres 2 routes to doing this, you can either go with a stroker kit which will run you about $1400 but give you good smooth power and much more reliable, or you can deck the block, thats not neccisarily gonna give you a lot of power or is it going to be safe but its definately cheaper, other than that, maybe a tricky little cam, and if you really wanna go all out you could supercharge it, i believe theres a paxton that fits the 390