Such a head was designed and patented by Alan Ross. It was then sold to Beseler and I think they still sell them. They are not hard to make. Beseler's are made of aluminum, but they can be made of wood or plexiglass.
You make a box that holds the negative that sets where the lamp house sets now. On this you place a 12x12 Aristo cold light. You can get one that doesn't have the transformer in it, but is separate to reduce the weight. If you have one with the xfmr, then you'll need to add a counter balance to your enlarger. The box, about 5" deep, can be reversible (top for bottom), with the negative drawer on the top for 8x10 or on the bottom for smaller negatives. The negative holder is a 12x12 piece of glass with the plexiglass diffuser hinged ( with tape). Immediately below is a place for another negative holder or filter.
The whole thing sets atop the enlarger less the lamp house and a few little pieces. The head assembly needs to be offset out a couple of inches from the chassis to clear the chassis as the head is raised and lowered. And the enlarger must be braced from the wall as the additional weight makes the enlarger bob up and back a bit too much for my use.
For 8x10 enlarging, you can use a 210mm or 240mm lens. I use a 210 El Nikkor and it covers no problem.
