what kind of oil

I use Amsoil in everything. Race car in particular has Dominator 5w-20.

http://www.amsoil.com/techservicesbulletin/motoroil/tsb mo-2007-08-08 flat tappet.pdf

You have to do some research to find oil that still has a decent amount of zinc in it. The industry has been reducing it in most of their oils, including diesels. Zinc & phosprous is not good for catalytic converters. It's getting to the point where the oil label needs to say "high zinc" in order to be sure.

For race engine break-in, I use a conventional oil and may add the Comp Cams stuff. Then it's Amsoil only from the above list.

Amsoil source & additional info:
www.thelubepage.com