Hey uniserver, check this out.
I got my adapter in practically next day. Very fast shipping! Oh man, it's like it was built for this mod. Fits perfectly. I got a couple plastic screws, and put those on the back 2 screw holes. They nestle in right next two a couple ICs, doesn't even move around. The edge of the adapter rests level on top of 2 oscillators. The power runs just to the side of the fan and can snake over to the power cable, and there's plenty of room to run the ribbon cable. My only concern is covering the fan with the ribbon cable. I'm going to try and split the ribbon cable so it's individual wires, then bundle them and snake it around just like the power cable.
That's a Presto 040 installed, so it fits just between the upgrade and the VRAM. An LC ethernet card is about the same width, so it'll fit with an ethernet card or cache card installed as well.
I was going to put in my MO drive which is perfect fit with a couple spacers, but I realized I need an additional 5v. I was thinking it might not work, but then again, it's a laptop HDD and an MO drive. It might be powerful enough to run both. I'll need to get a molex Y cable and give it a try.
My only criticism of the adapter is that the ribbon cable doesn't fit with the power cable plugged in. I may have to modify the power cable, use my Dremel to nip the corner near the connector. Should be fine, though.