Headers can be had from FRPP or summit. Also, the headers might work with 90deg. plug boots... my MACs do work, it's just all really close so I put some 2K+deg. heat wrap on them and no worries! It does make changing plugs a bitch, though... so maybe it's worth the $250 or whatever.
The frpp p headers or the mac p headers will make your life the easiest but I have seen guys using regular MAC or other regular style headers with the 90 degree boots. If you have some time it is worth it to hunt ebay for the headers. I got my FRPPs on ebay for $150 shipped NIB.
If you get the p specific headers you can still run the 45* stock style plug boots with out burning them.