Zach,
I would look for a used set which you can purchase complete with the manifold, heat shield, insulator blocks, linkage, and everything else you can get. My choice would be for the earlier HS style over the HIFs, but both are quite useable. You'll no doubt need to overhaul them or have a shop such as ours do the work for you. You can buy everything you need from several suppliers, including our host, brand new. Personally, I like the older product . They were die cast, and are of sturdier stuff. That said, we have installed some new sets with good success also.
Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon