Contrary to common belief that moultons cannot take 451 sized wheels, one of my mate discovered that TSR frame with V-brake pivots can take 451 wheelset. Of course you should compensate for different brake pad position with some adaptors or paul brakes..
Here is his TSR. He fitted a full dura-ace 20 speed groupppo, silver nokon cableset, thopson seat post and stem, brooks bar tape and saddle. Saddle is a modified B17. (Cutting brooks saddle is getting popular here too)
Personally I think that moving from 406 to 451 has less advantage than 349 to 355 or 355 to 406. You'll get less tire/wheelset choices with 451.
However, it's a cool mod anyway and there is skinny 1" road tire for 451...