With all the replica works bikes being raced these days I have'nt seen a honda six yet are they not eligible for the classic races they were first used at the end of 1964 so year wise it would be ,(just a thought!)

Cost might be a factor for something that you could only use at the Manx or Pre TT because of the not inconsiderable noise issues.  I believe the ACU grant a dispensation for those meetings/circuits.  It would not be a simple job to quieten it down for other circuits. A Gilera was brought out for the 50th anniversary of racing at Aintree a few years ago.  The noise meter must have had flat batteries that day.

The George Beale replicas would almost certainly be eligible and I'm quite sure that the noise wouldn't be an issue if the DED decided they wanted it to happen. I suspect the biggest stumbling block would be that they were £250000 to buy and probably haven't lost any of that value since. That's a lot of cash to risk on someone chucking it up the road or blowing the engine to bits (actually Hondas don't do that apparently, so it would be an 'electrical failure')

Can't imagine the organisers turning an entry for one down. Equally I can't imagine anyone running one. From what I remember the replica ones didn't go that well! I can't see it being easy getting one to be competitive without spending a lot of money and time on one.

They were well down on power compared to the real Honda 6's, I read an a good article about the copying of the engine and the basic thought was "just how the heck did Honda make this so fast and so well all those years ago". The crankcase and other castings were particularly difficult to replicate, the metal casting guy couldn't figure out how they managed it with the tech available at the time.

Just another case of the "Google experts". People think you can simply study something online for five minutes and copy it, simple....
Unfortunately there is one vital missing ingredient; genius engineers.