i did a simular setup as your thinking, pashley 26mhz frame with 80mm bombers ... wos so nice to ride, then i snapped the headtube, got it re-welded ... job done. Street bikes (dmr rythems/sidekicks) are different geo to a trials, just all the angles and mesurements are different alltogether ... rear stays tend to be shorter on a trials bike, and have a slightly higher b/b, so just be careful when runing suspension, due to the b/b will be raised a hell of alot!