yes, the upper rear A/C bracket is different for the HO. They are hard to find but maybe someone here will have one they would sell. They were reproduced by Barry at Sonic Motors, he had a run of 100 or so made and he might still have one. Their phone number is 810-750-1421.
On the vacuum switch, I think you are looking for the TCS switch that mounts to the rear of the intake. It's specific to '72 and part #1114454, might try JL Harper to see if he still has one of these:
http://forums.maxperformanceinc.com/...hlight=1114454