how high rpms on 360

How hi you can rev it and how hi of a rev is safe and how hi you in the rev you make power are 3 different things.

The cam dictates the power range, actual power may not top out in the cams listed rpm range.

Valve springs control the valves which are the first thing to not work up to potentail. If the valve spring can not keep the valves opening and closeing right, power falls off. This is called valve float.

Actual rpm has a limit in one other area. Oil surply. The stock pump in a stock engine has it's limitations that oil can only be pumpeded so fast. It is safe to keep it to 6000 rpm with a short burst to 6500 as pushing it. This should also apply to modified engines with HP pumps.

It is a safe bet that your engine is making peak HP by 6000 rpm.