My experience with the MP voltage regulators (early and late type) has been poor. Maybe they're buying them from the same company providing the ignition orange boxes!
The MP unit on my '62 is the same 4529794 you've been using, and it's held up OK for now, but that car doesn't see a lot of use right now. The Standard VR-125 is a good unit, as is the Echlin VR-38. As for cost...Summit are gouging on the Standard part, which can be had for under $31 from www.rockauto.com , and you may also want to check locally, since Standard/Bluestreak and Echlin are widely available without shipping charges.
Do make sure your regulator has a good ground...scrape paint off the regulator base and run a ground loop to the alternator housing and battery negative terminal, if necessary.