If they supply stands, then you're locked into whatever rockers and shafts fit their stands. Needle bearing rockers, such as T&D, Harland Sharp, etc., use a different diameter shaft than a bushed or factory rocker. Some rocker bodies are different widths as well.
The stability will just depend on how much stud engagement you have. I have pulled stand studs out of the heads at 600 lbs open pressure on aluminum heads. I don't know how much more base thread you'd have to have to get around that. My SOP for big pressure solid rollers is to just use race rocker setups. I'm thinking about how much you'd have to whack off a TFS head to get the T&D race rocker mounting bar to sit where it needs to......wow......