Vapour blasting is the only way....anything else and you'll loose the original 'grain'

I've done mine and it would pass for new factory look.

Vapour blast, dust coat 2k primer, de nib it, very light coat of 2k VW torando red, satin laquer (very light) then machine off with a 5 inch pad for the matt swirl finish.

Can get pics if needed......

Blasting will kill it and powder coat is way to thick