Put some x-tra fat tires on the hardrock and rock it hard!
I would think 26" wheels will allow a bit faster maneuvering than 29". Also, you already have a suspension fork and I'll bet that will be a big advantage if it is working properly. If I recall correctly, The Judy TT is a very simple fork and should be super simple to overhaul to get the best performance.
THere are not too many 29" wheel downhill or DS bikes being made... I'm not saying it can't be done, but the perfect formula hasn't been discovered yet.
Also, racing (any type of racing) is damn hard on equipment. THe heavy steel frame and old cheap nature of your Spec. makes it a better choice than your 29er.
BTW, what 29er do you have?