You can't really bypass the A/C, the belt will rub on the water pump. You'll need the FOrd Racing A/C delete kit to lift the power steering pump up high enough for the belt to clear properly
i ended up with about three different belts, with the AC delete from ford before i got the right one. I want to say its 72.0 inches that i ended up wiht, and thats with UD pullies
There's no reason whatsoever to bypass the a/c unless you remove it all together. When it's not operating it's just an idler pulley and does not rob any power. Your only benefit would be completely removing all a/c components for the weight savings, but there are no power gains to be had.
my a/c is completely removed, smog pump bypassed, with u/d's. i JUST put a new belt on my car and 72 should work nicely, i bought the wrong size before actually checking and after i measured, i went with a 72.5, but a 72 would also work. and dont be thrown off by u/d's, i could use my previous belt w/ my underdrives because the bigger crank pulley makes up for the reduction in the size of the alternator and water pump pulleys...not sure if that's the case all the time though