Some headtubes may be big enough dia. to fit the 1 1/8" and cups/bearings. I dont know how that steerstem is attached on a Girvin, maybe you can change it to a 1" without much trouble, otherwise cut and weld will be your friend.
I have thought of trying turned brass/bronze solid bearings, well greased, for something like this that the steerstem fits up through the headtube and yet has not enough clearance for the cups with bearing in them. Simple enough to try if ya have a lathe.....