I don't have the Hushpuppy but had my own 50 Razorback reamer made...or at least the likes. They were made by the same guy, Aaron Fouraker at Delta Company Arms in Yellville Arkansas (phone 918-332-6503). However he will not answer emails or that phone number.
After speaking with the owner of the company (call Arkansas Sportsman at 479-641-8850) it seems as if they had a bit of a falling out and he had no idea of a reamer or of Aaron's whereabouts. He did give me the number to a gunsmith in his area that had built a few of the hushpuppy's and he may have a reamer. I don't remember the guy's name or number but found this with some of my notes and worth a try:
Whitcomb Gunsmiths(479) 967-1387
If all else fails do as I did and make a couple of dummy rounds and send to Pacific Tool and Guage for your own reamer (they make GO/NO-GO guages too). Took about 3 months.
I have heard of guys getting away with the stardard 1-15" twist for .50 BMG's in their barrels. However I went with a faster twist because I mostly wanted to shoot longer bullets at subsonic velocities through a suppressor. I ordered an 18" with 1-9" twist but received a 25" with 1-8" twist. Whatever, seems to do the trick. I had it cut down to 16 1/4". Barrel took 11 months from Kreiger.