Help with my new to me 70 C10

[GMJimmy]

Being new to the classic truck scene I need a lot of help with my 70 SWB step side. I'm a mechanic but not familiar with a few things and would appreciate some help. When I bought this truck I was told by the seller that it was originally a swb truck but later learned that it was a long box. Yes I have dealt with him for that little fib and it wasn't pretty. The frame cut was cleverly disguised and I'm in the middle of doing some work to the frame to strengthen it and after that I'd like to change the leaf spring suspension to coils and truck arms. The rear gears are 3.07 non posi and I'm planning on an e rod engine and a 4L65e transmission and a posi 3.73 rear gear. With all that said I'm wondering if I might just look for a frame with coils and a 3.73 rear end. It would probably cost much less than buying all this stuff aftermarket but not too many of them around. After that I guess I'm going to look for some buckets and a console. I don't have a lot of space to work on this thing either so maybe the bolt on's would be a better way to go for me. Anybody have a frame or any thoughts?
Thanks.