The Model 67 Combat Masterpiece Stainless had a square butt until 1996, round butt after that. The red ramp front sight was catalogued from 1984 and may have been available before then.
The Model 15 Combat Masterpiece was a square butt till 1996. Red ramps were available at least from the late seventies. Most guns were tapered barrel variants, there were a dew special orders with a heavy barrel.
The 686 has a deeper cylinder window and larger cylinder. So the gun is heavier even without the heavy barrel. If you are interested in these then try and find a 686 SSR, this is a 4 inch, tapered, flat sided barrel gun with round butt, white outline rear sight and interchangeable front sights.
It has a premium price, but may be worth it due to the balance being much closer to the trigger.