twin turbo = t3/t4 50 trim, .63 a/r back side. good spool and will suport 800~1000whp.

single turbo = t67 for 700~800 with great spool or gt4202 for decent spool up to 1000whp.

i personally would go with the single t67 if this is going to be a daily driven truck that you want good response and a decent amount of power. single is a easyer and is nicer to your wallet.

main thing your going to have to address is the fuel managment. carb ain't going to cut it if you want it to run decent.

i would look at autronic, fast or haltech for an ecu.