If it's a case of either being okay for your budget, then go for the 32' by 65.' If you do a full back straight into a sweeper, that's a decent high speed section. And assuming 8' lanes, the remaining 24' of depth translates into an infield three lanes deep, which is just fine for your twisties.
We run a non-profit track out here in Seattle, and it's going great. Good luck.
Seattle RC Racers
The world ends when you're dead. Until then, you got more punishment in store.
Stand it like a man, and give some back. --Al Swearengen