[Aussie Mike]

Clevelands can tend to run hot. I spent ages trying to get mine to behave itself. One thing that I found was a factor in getting the temp stable was ignition timing. Don't trust the timing marks on your balancer, I've been caught out before. Do a TDC test and mark your balancer with the right TDC. I drilled out and tapped an old spark plug and then put a bolt through it to make a piston stop to check it. I had the curve in my distributor reset and set it up with the specified static advance and most of my cooling problems went away.

I've found my Cleveland is happier with some water flowing through the heater hoses too. If you aren't running a heater you should conenct the 2 heater connections together.

For the motor to make 511HP it'll probably have a fairly big cam. Mine had a reasonable cam and ony pulled 10 inches at idle. With your Holley you might want to check what power valve you have in it. I've found that if the vacume at idle is very low the powervalve will open and dump way to much fuel into the motor. You will need to drop the power valve number to be under the level of vacume at idle to keep it shut. There are probably some people on here who have had more experience with Holleys than me so they may be able to confirm this.

Hope this helps.

Cheers