The modern 3W has too large an engine for ACU competitions. It may be eligible to enter sprints / hillclimbs under MSA rules as far as I can see, plus car trials...
As far as I know, the MSA won't accept it, wrong number of wheels! The period exemption that some Morgans have, I think, has a cut off date of 1934. I believe however the ACU will accept it for straight line sprints, but not races, twisty sprints or hillclimbs. (I think this was in the Bulletin).
