Camshaft clearance

If I am wrong someone correct me....but aren't the cam lobes tapered? One of the effects of this is the that the lifters bearing on the lobes (because of the valve spring) forces the cam rearward against the cast iron block. Normal operation will keep the cam in place. Also the taper causes the lifter to rotate, equalizing wear.

Having said all that, I welded a nut into the timing cover and using a screw and locknut, have adjusted my cam endplay to .020 (.5 mm)
Mostly because I could and maybe I'm a little eccentric . Got the idea from slantsix.org