I'd aim for 5200-5500 in that range. It more important though to make sure the max timing advance is set correctly, before you aim for max rpm. If the max timing is too far advanced, then you might just melt your pistons.
I am not sure what its set for on your's. These motors are mechanically set with a "tool". however you can also time them using a timing light, or a dial indicator. I think yours is set at .235 btdc, but I am not sure. Others here will know for sure.
Here are a couple links to help you out. http://www.maxrules.com/timingindex.html
This one is from the service manuals. http://forums.iboats.com/showthread.php?t=168855
This one will help you understand what your trying to do, and how to adjust it with a timing light.
