what is your thinking in wanting to use a straight 30 wt. oil as opposed to a multi viscosity oil like a 5w-30 or a 10w-30 ?
the multi viscosity oil will flow better while the motor is cold, which is when most of wear occurs.
as far as the break-in additive goes, I would leave it in for no more than 250 to 500 miles, and try to get those miles driven in a short time period. Then be sure to change the filter when you change the oil.
Many, if not all, break in additives contain graphite. It can make your oil filter much less effective (plugs it up) and should not be used when normal oil & filter changes intervals (3000+ miles) are employed.
I don't think a break in additive is necessary. Just my subjective opinion. When my engine was overhauled 43,000 miles ago there was a liberal amount of assembly lube put on the cam and lifters. Otherwise, no additives in the oil.
Z.
p.s. nice looking engine by the way.