Still overheating

Hey guys,

I'm looking for a little help with troubleshooting an overheating issue.

My Scamp has a /6 with maybe 15k miles on the rebuild - bone stock. Radiator and hoses were replaced at the same time (about 6 years ago). The symptoms are that it slowly runs to the hot end of the temperature gauge (over the course of several highway miles or sitting in city traffic) and spews coolant from the overflow hose when I shut it down. It usually diesels as well, so I've taken to shutting it off in Drive. Besides the overheating, it drives and idles fairly well.

I replaced the stock 195 thermostat with a 180 performance. Still overheated.
I adjusted the timing from 5 degrees advance to TDC and readjusted idle to 750 rpm in Neutral. Still overheats.

Dwell reads at about 39, which is slightly low (manual says 41-46 :read2:). I'm not great at adjusting points, so I was going to hold off on that until I thought it might be the cause of my troubles.

The upper hose is hot, so water is circulating. Water pump sounds OK - I mean, no bearing noises. I rechecked the coolant level last time and it was OK after topping off for the lost coolant.

I'm a little frustrated because this 225 should be bulletproof, and before Winter, I had an extended drive in high ambient temperatures without a problem - temperature sat so low I thought the gauge was wrong. Any help/ideas would be appreciated. I want to start commuting in this car again as soon as I can.