400 block worth saving or junk ?

[sleepertruck72]

I tore down the 400 block that was in my truck previously. It is a 2 bolt main casting # 3951509. The cylinder walls only have 3/16 of an inch between each other according to my tape measure. I dont have one of those mechanic gauges or whatever is used to measure all that. The motor smoked a little on the freeway before I pulled it. Is it worth rebuilding or is is not able to be bored anymore ? It all came apart pretty easy. Thanks for your help.