Break-In. How Long?

eek,
I'd make sure you know how much mechanical, and vacuum advance the distributor is giving by using a dial-back timing light. If there is too much full total advance, it could cause missing at 3500 rpm and maybe damage. Make sure the distributor has the right advance curve. Do not assume it is right.
I've assumed nothing. It Is right, Rebuilt and Dialed-In for My Car by @halifaxhops. Low teens initial and low 30's total.
I fixed an issue with the Resistor swap, It's a Non-Issue now.