JAWS 56 Chevy Stepside LS Build

[jaws61]

Hey Guys and girls
I"ve managed to get my hands on a a great 1956 chevy stepside truck, This is going to be my second build but this is a lot more of project compared to my last one. So i'll be asking for a hand and idea along the way.
Down to the truck
Its a 56, The floors have been all welded in and the cab corners have been lapped welded but aren't completely weld in solid. Should I be welding them in solid, the doors are the same way. The biggest catch with the truck has a new roof put on and its got a lap joint on the rear and I'm not totally sure how I the line to disappear?

Now to my parts list, I"ve got a Horton weld series IFS coil overs and tri angle four link, C notch and a chevy S10 rearend with 3.55 gears and disc brakes.

First action was getting the cab of the frame and the doors off the truck. Then planning on boxing in the chassis and before hand weld in some c chaneling to make sure the frame doesn't twist and I'm also going to put a tubing in front of the front cross member..

I'm planning to run a 5.3 Ls and still looking for a tranny for now. I'm also looking for a 6.0 too.
Any ideas or help is great!! Thanks for coming by!!