They are "don't float your valves" Schubecks
great for cam swapping
for production
"We run cast cams, and our oiling lifters, for up to 440# over the nose.
For anything over that, we go to steel cams, and coated tool steel lifters."
But for a dyno run the ceramic lifters should work
wish they had been available when doing "wheelbarrow of cams" tests
easier than refacing lifters