I ran an OPS Gold Head 'back in the day' when I lived in the Denver area. Also used an OPS pipe. The engine will turn a 11x7 size prop in the 14K+ range but you have to be very careful with carb adjustments. It is very easy to get too lean with that carb due to it's large intake area. The thinner air at the 5000ft elevation certainly contributed to the marginal fuel draw capability of the carb. I eventually went to a ST carb with a smaller intake area to increase fuel draw capability and the engine ran much more consistently with that setup. However, if you are at a much lower altitude, the stock carb might be just fine.

The Gold Head is designed for high rpms and probably won't be too happy with props larger than the 11x7 if you want to run in the 14K rpm range. The engine was very robust, I never had any mechanical issues with it and ran it for several years. Well built and will certainly 'howl' when set up correctly.

Woodie