I have a set but have yet to run them (hopefully here soon, I want the damn car out of my garage and on the road where it belongs). I bought them bare and sent them to Mike and MRL to build because at the time he had the greatest knowledge about them. I know he posted some builds he had with them and at one time sold them here. When I spoke to him he said he bought them bare and the guides were not good quality so he replaced them on every set he built. He never mentioned the seats. He also said the ports needed some help (what head doesn't as cast so I can't speak for the CNC ones) and worked mine over. My Comp Magnum (not Pro Magnum) rockers didn't line up well. I got a kit from B3 but they raised them too high and back I had push rod hole clearance issues (so you may want to open those up). Hughes rockers fit spot on, but that was with the valve heights on my heads. Head bolts for Edelbrocks work with them. Alternator fitment is tight (as is with Edelbrock). I believe the exhaust and intake threads were heli-coiled, might verify that with Speedmaster that they are. My Doug's headers and Stealth intake bolted up with little fuss.
It's a tuff call, this stuff ain't get'n cheaper. I hope someone with more experience than I chimes in. I'd like to know more as well.
