Gatlings were refined over many years back in the 1800\'s and early 1900\'s. Very few pictures are around of ones tripod mounted, most were mounted on field carriages. No doubt this was due to the guns weighing around 300lbs. I wouldn\'t be surprised that different versions of tripods were used over the years.
As for the scaled replicas.... most are only semi scale replicas, not exact. Individual builders do their own modifications to the guns, usually improvements. I have done two tripods for gatlings, neither was a exact scale replica. They were not even replicas ! Mostly this was because after much searching I could not find decent pictures of period original tripods, only sketches.
The main consideration is that the tripod be VERY sturdy. My .357 gatling weights a bit over 70lbs empty, not including the tripod.
The D&E 22 rimfire gatling plans include tripod plans. The D&E gun was scaled from a original gun and is quite accurately scaled. I would guess their tripod plans are accurate replicas also but its only a guess.
Another possible source would be Colt, they are offering a true replica gatling through their custom shop, it has a tripod. Here is a video of that gun that shows the tripod.
https://www.youtube.com/watch?v=ildteJbZ9Jw&t=279s