tlorber did you use the short or tall cab mounts.
this is my 49 truck with the short mounts and 235/75/15 rears, which are 2" taller than a 255/50/17. I usd 3" front springs and 4" dearched leafs. bed done the same as you, the stock s10 floor grafted to the 49 bed.
IMG_5254 by
Joe Doh, on Flickr