Vanstrom Performance is around that area, does awesome work, he works on a lot of mustangs. Builds a hell of a nice car, I'm sure he can help you out. I don't have his number with me, but he's a member of the club.
Putting long tubes on my 69 mach was a pain in the rear. My son fox wasn't to bad but he had short or mid tube headers. They all take a little finese and time to put on.
I've put motors in both ways with the bell housing on and off. I like it on, then you only have to both the transmission up to it. I assemble the motor leaving the carb and distributor off with a clean rag in distributor hole. I put the headers, along with the pullies, fan and etc on afterwords...