I'd sure like to see photos and hear more about your Cummins/Chevy swap. I have a crew cab '88 V30 (K30 to me since it is one of the last of the real Chevy trucks) that absolutely rocks with it's 454 and Chevy bulletproof driveline and suspension, 35" BFG MudTerrains, custom oak and leather interior with front and rear buckets with console jumpseats, etc. It makes my x-cab Dodge look small.
I would love to do a Cummins/NV4500 swap in it someday. It would take a pretty good Cummins to outdo the built 454 in power and driving pleasure, but the fuel mileage is what you might expect... She doesn't get driven much these days, neither does my Dodge, but it never fails to put a smile on my face and turn some heads.
My 14 year old son plans to drive it to and from school this fall. Only 6 miles each way, so gas won't be too killer and nothing is worse on a vehicle than just sitting. I'll rest easy knowing any deer that hits him will barely feel like a speed bump, too.