We have a turbo LM7 swap in our 69' C10. Stock 5.3 short block with ARP Fasteners and Head studs, 6.0 heads, ZR1 Head Gaskets, LS7 Springs, LS6 Cam, stock truck intake, home made crossover buick style header, S400 style turbo, water injection, 60# injectors, 255 LPH pump. We have gone 20 PSI on it before with absolutely no issues!
Trans: 4L80E with a Shift Kit, and 3200 Stall convertor, Using a 4L60E in a modded LS application is a complete waste of money!
,Dan