Boss 330's on my 77 cheyenne?

[Gmc_graff]

Alright im trying to decide on some rims for my 77 and i really like the boss 330's . I was gunna buy these back when i had my rcsb 03 sierra but went with some boyds instead. But now that i got another truck i wanna see if these will fit. I plan on getting a 4/6 drop to . Or does anybody know what sizes i should be looking looking for like the width,back spacing, tires size any help is appreciated thanks . Ill try and get some pictures of my truck