Rectifier Bridge on heatsink?

Mount it to the chassis and run it hard for several hours. If the thing stays below a "reasonable" temperature, you're good. If the rectifier gets too hot for your own comfort (or too hot to continue functioning), then you needed a heatsink. Add one and try again.

Without giving more detail, that's about as good an answer as you are likely to get.
Thanks for the help all. I figured the base plate would work. The amp I am building is a stereo ESP p101.

to amplifierguru:

I'm running 2 x 22,000 mfd per Rail. Total of 88,000 mfd.

to AndrewT:

I haven't done any detailed calculations about peak currents. Any equations?

I'll hook everything up and let it run for a while to see if it heats up excessively.