I don't remember the brand, but I purchased from Winchester auto, who usually has quality stuff in stock (never had an issues with their parts or gaskets).
My mechanic checked for flatness and it was to spec.
The block and head were cleaned and scraped thoroughly of all materials using hand tools and scrapers, head was sanded lightly with higher grit sandpaper.
No chemicals that I remember using during re assembl, just motor oil for the head bolt threads if I recall correctly.