What oil's for flat tappet, stock LA Cams ?

Mobil-1 15w50 has the extra zinc in it for flat tappet cams and is available at walmart

Yes, it's specially formulated for flat tappets according to their website and product sheet. Just that one weight, though -- don't sub any of their other products. I have been using it in my Barracuda and also in my MG, which ate its previous cam and lifters running the factory recommendation, Castrol 20W50.