There were 2 sizes of the original factory grips. The COMPACT grip was available on the 3" and 4" Fixed Sight GP100s. The full size was available on the 4" and 6" adjustable sight guns. The COMPACT grip is very rare, and commands a high price. It uses wood inserts that are the same size as the SP101 grip, with a cutout on the backside for the grip locator pin. Again, these are very hard to find, but it is a great grip for a GP100 that you want to conceal. The only place I have found the COMPACT grip, is Ebay. I have 3 sets now, one for my 3" GP100, one for my 4" GP100, and a spare I picked up this past friday night, with original wood inserts, for $30. One set ended last week at $167. You have to watch constantly, and act fast, when they come up with a "buy it now".
The full size grip can be ordered several places. MidwayUSA usually has the bare grip body, You will then need wood inserts, screw, and grip locator pin. Altamont sells a very similar grip body(it has some decorations on the front, and back strap), and they also sell wood inserts. ChigsGrips has the Grip body, fancy wood inserts with screw, and the grip locator pin. The inserts in my family photo are all Chigs inserts, made from Cocobolo. He is probably your best bet for the full size grip set, because he has all the components to replace your Hidious Houge with the original, full size grip style.
Just to give you something to look at, heres a family photo, the 3" and 4" guns have the COMPACT grip. The 6" gun has the full size grip. Then the 3" with the inserts its wearing now. I just got a set of the same inserts for the 4"
