But what about oil, because of the 235 flat tappet cams? wont any oil without zinc destroy the cams?
NO.
Today's reduced ZDDP oils are only down to the ZDDP levels of pre-1970. If your engine is stock 235 1961, and if you used a good "assembly lube" on a GM/Chevy camshaft you will be OK.
It's like Y2K and the Mayan Apocalypse of 2012, everybody says its true .... I am still waiting for someone to prove Chevrolet needed high levels of ZDDP in breaking-in stock cams on 235 Stovebolts. I await the "Google it and see all the stuff on the Internets responses"....and I still wait to see it in TSB or Chevrolet literature of the period.
Todays ZDDP levels in oils are good for your cam. Don't Panic. They are Ok.