Thank you and no, it's an NOS 20" Akisu fork (stamped AKISU 83) which is about 15mm shorter axle to crown (bit less mudguard clearance and might be tight for a 451 wheel?) and has a shorter non-foldable steerer - picture below next to modified kingpin fork.That green one is a bit special. Did you have the fork chromed?
Rides very well and about 20% lighter than the std fork. The one in the picture might go on KingRat (fixie) as I have a senseless urge to see how light I can make a folder without spending lots of money.