Ive used dozens of these on Mopar and Brand X engines without any issue..I copper coat them (two heavy coats and install wet)..I even used aluminum matallic paint on one set as I had no copper coat and had no issues..(Ive used the paint before on steel shim gaskets)..

Its best to have nice surfaces, but even on the ones that arent dead perfect, they held up good..

YMMV

MB