FT cam only. Repeating what I said in post #9. Lifters that are used with FT cams develop a wear pattern. When new, the lifter face is convex & the lobe has a taper front to rear [ or rear to front ] depending on where the lifter is positioned in that engine. After enough miles, the convex lifter has worn, such that it could be flat or could even have a slight hollow in it.
Moving those parts to another block that has the lifter bores at a slightly different angle or front/rear location in the block [ machining tolerances ] can result in the lifters no longer spinning in their bores [ lifter/lobe failure soon after ] because the built-up wear pattern is no longer there. Using re-faced lifters ensures that the lifters will rotate to distribute the wear.
The above is based on the assumption that the lobes/lifters in question are still in reasonable condition.
