Picture time.
This is kind of what the lay out will consist of.
The heat sink I am using for this is one just like I pictured but with about 1/3 cut off it and painted flat black.
On my big AC to DC welding machine conversion I run these same bridge rectifiers at up to 100 volts and at 25 amps each for 90 seconds at a time when I burn an 18 inch long 3/16'' 7024 electrode. They are on a slightly larger heat sink with a fan.
This application will put one bridge rectifier on a big heat sink, with no fan and only up to 20 amps going through it continuously.