[PeteVS]

There was an article in Hot Rod a while back that explained (and I don't know if this applies to OHV's only or all engines) that the lobes on the cam have a very slight taper when viewed from the side and lifters have a slightly spherical shape on the ends. This allows the lifter to contact the cam somewhere off center, causing the lifter to rotate, a bit like a ring and pinion. Thus there is really no sliding contact. If both surfaces were flat, they would both be wiped out fairly quickly, especially with the higher spring forces found in OHV engines.

Having said this, I'd say give it a go! There might be enough taper to get the required action.