guys, tnxs for confirming my thoughts on AL=steel..... exposed to elements is another story of course, TT.
Mirko, if you are in need of shimming material, just come and grab some next time you are in milan.
if not search for Hasberg shims
would design say for nominal 0.5 shim so you can go both up and down in .1mm steps
for X, cant see the problem making the holes a bit oval, with 4 M8 bolts (?) exerting a few tons of grip it's not going to go anywhere....
you are in good company, even works GP hondas had to shim their cam gear drives