Help on Gas Tank and Wheels

[mothertruckr]

I am about to acquire a 1965 C10 swb step-side 2wd project truck. Im probably going to do a rat rod/hot rod project. I am trading my Chevelle for this (its a 72 355ci motor built to the hilt making 400hp give or take. But needs int/ext and trans work. which is why im trading tired of having a car I cant drive and dont have time to work on).
truck has a new 383 stroker (11:1 comp) with a built 4 speed auto and ratchet shifter.

So to my questions:
Sending unit in tank is bad. How hard it it to replace? Or on a 40+ year old truck should I replace entire tank OR put in a bed mounted fuel cell??

Also I am looking for rims. I understand the bolt pattern is 5x5 (5x127) on these trucks and from what I have found stock rim was a 15x7. This truck is lowered 2inch front and rear. I want to run a 17x8 (4.5 backspace) cragar, wrapped in a 255/45/17. Is there any suggestions on this? Anyone know if ill have clearance issues?

Also I was going to order a hood from unlimited products. I believe its a bolt on fiberglass hood, Anyone have any feed back on them?