Timing: Power & Rattle v. No-power & no rattle

[Austin C10]

About a month ago, my 1972 Chevy started experiencing some rattling on acceleration. Initially it was only when I got on the gas pretty hard. But then it was every time I touched the accelerator. I experienced a pretty significant loss in power, too.

After tuning it up, I took it to my favorite shop (I'm just not in a position to be messing with timing right now) and they adjusted the timing making it real quiet. They said that the harmonic balancer was old and had slipped, and that the most quiet setting was about 10 degrees above top-dead center. But this pretty much sucked the life out of her. No jump at all. On my way to take it back to the shop, I had a total electrical meltdown: short and the fusible link burned up.

Does anyone think that the timing adjustment could have played a role in that short? I didn't think so, but it is an odd coincidence.

Anyway, they replaced the harmonic balancer and re-adjusted the timing with a timing advance to give back some power. Well, the acceleration rattle is back. The shop owner said that the engine is old, and that I can have one or the other: proper timing with no noise and no power, or pre-explosion and some pep, which I assume is going to kill the engine. Should I buy this? I mean, the harmonic balancer is new, so is the vacuum advance. Why can't top dead-center of 10-12 degrees give me full power and no noise?