Peter, I'm all in favor of keeping long-legged passengers comfortable! If you relocate the stock alternator to the area above and back 1" from its usual place ala' the GT-5 and later cars bracket, the alt' can be driven by the unused second crank pulley groove. That move can allow a MUCH smaller custom firewall blister around the water pump only, and the passenger seat will then adjust all the way back to the firewall. She will be happy.
If you find or duplicate a stock post-1980 engine bracket for the alt, smog pump and A/C, your stock alternator will bolt on in place of the seldom used smog pump, with 1" cut off the front of the alt's casting mount and the cut aluminum piece used as a spacer on the stock bolt. There's an illustrated article on this in the POCA Newsletter Archives some 30 years ago. My wife used to drive our Pantera about 50% of the time so the 'long-legged passenger' was often me!
Happy cruising!