My Romak scope doesn't fit the rails on the Centerfire Romak receiver or the scope rails that came with my WUM kits. The scope does fit several other AK-74 rails I have though... Hmmm...
IIRC from the earlier discussions, the rail requires a 60 degree dovetail cutter bit for the mill or a 60 degree dovetail file. In theory the barrel should be parallel to the top rails of the receiver, so the scope rail should be parallel to them as well.
When I do my Romak rail, I'm going to clamp the receiver to some blocks on the mill table and adjust until the top rails are parallel to the X axis and the side surface of the receiver is parallel to the table. Then I'm going to install a dial indicator on the head and zero it on one end of the top of the rail. I'll just jog the table and watch the dial. If there's any substantial variation, I'll install the cutter and take off the minimum amount from the top of the rail to get it parallel and zeroed. Then I'll move to the bottom of the rail and take off the remainder to get the scope to fit.
If necessary, I'll run a cutter across the outer face of the rail to knock down any high spots that interfere with the scope. Since the locking lug forces the scope away from the rifle to engage the dovetail surfaces, the outer face of the rail shouldn't be a problem (I hope).
Take a look at the locking lug on the Romak scope when you rotate the lock lever. The lug doesn't move that far, so any excessive narrowing of the rail would be REALLY bad. The rail should be narrowed just enough to let the scope slide on to the dovetail with some drag.