Well I've ordered a used HRP-600-15 off of ebay for $42.99 as well as the 3-phase rectifier, so we'll see how this goes. I'll look into bypassing the psu's internal rectifier if the voltage isn't enough as is at low rpm driving. I'll order a fan once I get it installed and get the car back on the road.
Thinking of going with a manual kill switch rather than using a relay. That way maybe I can dinker with doing a little bit of "alternator-less" driving, and more importantly turn off the PSU at strategic times if it starts to get hot. A basic 12v battery kill switch like
this should work, hooked up to the ground lead coming out of the meanwell.
This should make rebuilding and recarpeting the rear a bit easier with not having to work around the stock DC-DC converter, but I wish it had happened on my timing, not as a result of one little broken bolt.