I had someone who I trust and knows a lot more about antique gunmakers and flintlocks than I do take a look at it. In my pictures the hammers are at half-cock. At full-cock they are a lot further back and he immediately said that it seemed like a long way for a hammer to travel to ignite a cap. His opinion was that it was a flintlock that had been converted.

That is a very valid point - I have heard that before.
Apparently, the greater distance through which the hammer falls (pivots) allows it to build up more speed & the flint will hit the frizzen with a faster (harder) strike.
All of this extra distance/speed is of no value to merely set off a percussion cap. Excess force will merely batter the nipples.

Thanks for the comments John, I know there are different views on this, but I would like to re-convert this back to a flintlock.

If you think about it, it was probably a flintlock for 25-50 years and a percussion for 125-150 years. I have been wanting an original/antique upland sxs flintlock and finding a good original is both hard and expensive. Converting this one back to flintlock would make it "correct" again and give me something nice I would actually use on occasion.

I need to find someone to do the reconversion and will do that after the new year. I think it will be a wonderful gun back as a flintlock.

Jay, IMO, your gun was definitely made as a flintlock. And it has the original Manton Style patent breech which is still there. Reconversion to flintlock would be discouraged. It can be done but a quality job by a real pro would probably cost in the vicinity of $5,000 to $10,000. Castings could be used but it would always look like a cobbled together piece and the reliability of the lock would be doubtful. An oxymoron is a “good, cheap flintlock”.