fuel injection

The best inexpensive solution would be a used Holley Commander 950 TBI kit, ~$600 on ebay. Even cheaper is modding a GM TBI, like Howell Engineering does. The Holley Pro-jection is cheapest, but doesn't work near as well, though their very last 4 bbl Di system looks close to a Commander 950 (more sensors). If you buy new, most TBI kits are $2000+. I don't know if anyone makes an MPFI intake for RB engines. Might be a few rolled-my-own intakes out there.

For more HP, you can search for bigger injectors for any of the kits. One thought I have is an MPFI system with small injectors for good mileage and driveability, with a TBI to add fuel when you need the power. Some factory designs are going to that now with 2 injectors per cylinder.