Break in oil ?

Use Joe Gibbs Driven break-in oil BR30 (5W30) or BR (15W50).

http://www.drivenracingoil.com/dro/br30-break-in-oilhtml/

This oil is made for exactly that purpose, breaking in a cam and lifters.

I attended a seminar by Lake Speed JR who is Joe Gibbs Racing Certified Lubrication Specialist, and these guys know what they are doing. Their flat tappet NASCAR race engines rev to over 10000 RPM.

The BR oil should be used for no longer than 400 Miles according to Lake Speed JR.

It's pretty pricey stuff but worth every penny considering all the work you have put into the engine.