There is a few threads on this already, but I'll type it again.
What trans do you have, 4L60 or 700R4?
NEEDED PARTS: Older HEI distributor, Fuel pressure regulator with a return line ( Holley 12-803BP or Mallory 4309) Carbed intake for your motor, Carb.
If you have a 700R4, you might be able to use the TV cable bracket off your old TBI motor, or buy the bracket from Summit for your specific carb.
Links for Edelbrock, Carter, Quadrajet carbs.
Throttle lever for Edelbrock carb
TV CABLE bracket
Links for Holley carbs.
TV Cable bracket
Now if you have the 4L60, you'll have to use a TPS on the carb.
Step 1: you'll have to use a fuel pressure regulator with a return line if your gonna use the in-tank pump, without a return line you'll burn up the pump fairly quick.
I'm using a Holley 12-803BP $80. shipped through Summit.
Step 2: Hei distributor, use the pink & white wires that power your coil to power the HEI.
Cut the wires going to your coil, Pink = power, White = Tach. and attach them to the HEI dizzy.
Step 3: keep your Oil pressure, water temp, alt, and AC wiring and hook up like normal and all your factory gauges will function the same as stock.
Step 4: remove all unused wiring like O2 sensors, TBI, and anything else not being used and heat shrink them.
Step 5: drive it like you stole it.
It's a really simple swap and I'm sorry for the novel but that should answer your question.