NBS LTs will mate for use in OBS swaps, but the engine placement is key (esp in pre-87 trucks like mine). I moved my engine forward to accomodate for use of the stock truck compressor. I notched the pass-side frame rail a bit b/c I could not find a set of factory F-body manifolds, and got impatient. Gotta box in the rail for strength purposes, but that's all.

All on what you want. The NBS LTs (IMO) would work if the engine was placed closer to the firewall.