They sold kits that would either convert a street bike with a rear swingarm or some places sold frames that would take those engine. At first glance they sound pretty powerful, but they weren't really. Unless you have alot of wide open spaces to open it up, it just really isn't all that. They worked ok in a bike, but were never really meant for a trike. The novelty is kind of cool. But they are heavy and cumbersome and not manuverable. You will have bragging rights while having though. Hopefully it's one of those kits and not just some cobble up piece of junk. Best of luck with whatever you decide to do.
Nicholson 500x (Project)
Nicholson 185s
Nicholson 110 (That takes an atc70 tank)
Ascott 500 head/350x (Project)
Homebuilt Racer Chromoly Suspension 110 (Ragin Runt)
PK Racing Suspension 70
A+ Inc Suspension 70
AWS Aluminum 90 frame
Hi Performance ATC Suspension frame rd350
Hi Performance ATC Suspension frame 90