The ones with stepped up tips.....you want the point of contact as close to the rocker as possible, because the pushrod moves to the side throughout its lift, (unless you have perfectly inline pushrods/lifters) and canted engines do not.
The correct way is utilizing a 42/46 lifter location along with (on 351 fords) a 1.850 or larger lifter spread to minimize this. The 42/46 location works well on BBFords as well
If one is to operate in extreme rpm range valvetrain geometry is the most important issue to get right.
Notice that I said valvetrain geo, that means the whole system.
If the rules do not allow the modifications that I stated than you revert back to my first sentence.....step the ends up as close as possible to the tips.
The store bought Manely's as stated above are the best off the shelf piece for Fords as BBChevy already have rotated lifters
Just one of the obstacles to overcome when building a 2hp per CI stocker...Wait...., the toothpaste is out of the tube now...
