Imo, 1.2mm(.047”)and 1.5mm(.058”) aren’t really all that thin.

1.2mm is .004” thicker than .043’s, and 1.5mm is only .004” thinner than 1/16”, along with 1.0mm being only .004” thinner than .043”.

So....... how much is .004”?

About this much:

277E7338-30F7-4B62-9BD0-1B907225E2A3.jpeg
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads