Cooling issues 69 Dart GTS 340

Update on heating issues. Changed to a 16lb cap. This stopped the overflow problem. Pulleys have been changed 6 on crank and 5.2 on fan. Took it for a cruise Saturday. Ran 210 for long time then started to crawl up to 225. Not happy with that result. Has any one run a Flowkooler high flow water pump? Thinking about trying that next.