To clarify, I do not have the variable condenser head, but the older single condenser. I have been doing 2X2 with the long lens, and it works, but it is limiting ,not just in how big you can go, but when you do crank it on up, the easel ends up way up to, and sometimes almost hanging over the edge of the baseboard.
I tried the 80 on the cone that that the 135 is on, and got huge fall off, so i tried a flat board, actually not completely flat but with a cone of about 1/4 inch, with the same results. So, my conclusion is that contrary to what some have written, you really do need the correct condenser. Bummer since they don't seem to easy to find, and are be pretty spendy when you do.
A better solution in my case may be to just build a table for the enlarger with a drop bed, so I can get more height, and better centering of the easel, and just use the 135 with the condensers that I've got.
My suspicion is that people did exactly that sort of thing when these were new, as you see a lot of these enlargers with the same focal length lens/condenser combo. I just wish the guy I got mine from was still around to ask how he did it.