Thanks for the comments. We're very happy with the result.
To the questions:
Yes, it's a 6.0l gasser. The wife nixed the Duramax diesel...
The high top is the reason the GMC won out, as I'm over 6" and even with the Voyager top the inside standing room was only 6"1". The GM version of the Voyager top is taller, and gives 6"5" standing room. We've had a Adventurewagen Vanagon for 20 years, and we both are so used to standing up freely inside at all times that the penthouse top was crossed off the list pretty fast.
The tires are BFG TA/KOs, again a carryover from the Avdventurewagen. They are 265/75 16s, and the wheels are American Eagle 186 series 16x8. Both the tires and wheels rate out at about 3,400 lbs per wheel, plenty of margin for the GVWR of 9,600 lbs. There was a minor trim inside the wheel well, but the fenders are stock.l No rubbing so far, although the van hasn't been off the pavement yet.
We'll find out next week a bit more, as the plan is to start off in Death Valley and do some mild off-road stuff to break in both the van and the co-pilot
John