So if you had the chance to ask Bob Sharp just one question what would it be?

Here's some general areas you might think about for your question:

Racing in general

BSR race car drivers (Fitzy, Sam, Paul, Walter, Paul, et al)

Competition (other drivers)

Managing a race team

Interactions with other race teams

Interactions with Datsun/Nissan/Nissan Comp/Coventry, etc

I doubt Bob will remember technical details like what camber settings or cam profiles did you use in the 1985 300ZXT that Newman drove. I know I can't remember every detail of my set-up and my season ended 6 weeks ago.

A few years back I asked Bob if he could only get to drive one of his race cars which one would it be and he never hesitated - "the GTU car with 15 inch rear rims", "I could put that car anywhere". 

That GTU car with 15 inch rear wheels sure looked effective, I'd ask BS how much to hire it for a day.

How did he deal with the early crankshaft vibration in spring of 1970 and did it cause a DNF?

Probably a waste of time but does he have a lifetime supply of Newman's Own?  I'm sure he does, that's really good stuff.  I like the Italian Light. 

I think I'll pass on the PLN sauce question but I will look in to see if there were any DNFs in the first two years.

As to renting out the GTU car, you're out of luck if you wanted to drive the #33 car as Bob crashed that at Road Atlanta when a rear tire blew doing over 150 mph. He rolled it at least twice if not three times, The #38 GTU car that Fitzy drove is privately owned and as far as I am aware it has not been run on the track in many, many years. If you had $$$$$$$ you might be able to buy it.