I thought the Indian made REs were accepted by the AHRMA. Shouldn't be too hard to find out and it would sure be an interesting project, good luck.
Yes, the Indian made Bullets are accepted in AHRMA.
The AHRMA road racing classes have Indian made Bullets racing there.
I think if they allow it for the road racers, they'll allow it for the trials too.
From what I've heard, it has to have the 4-speed gearbox, and not the 5-speed.