I was a bit concerned about space too until I tried it out. I have the adapter rotated so that the flat section is toward the rear of the car and angled down about 15deg. Since it doesn't screw on, you can rotate and tighten it in any position you want. The center is drilled and the threaded piece is a male to female adapter that screws onto the existing oil supply pipe coming out of the block. That was the part that I was a bit worried about (they should explain that on their web page). No matter though, it can be positioned at any angle.

I screwed both of the new senders into the "flat" embossed section of the adapter and plugged off the two taps on each side of the adapter. I positioned the oil press bulb at the top, and the temp sender at the bottom. There's actually a ton of room when you mount these facing aft (out of the way of the alternator and press sw.).

So if you have the 2 prong setup with the press sender/dummy lite switch, you can just use the switch and get a second press sender that matches your gauge resistance. Bottom line is that you'll have to re-install what you've got otherwise you'll need a plug to cap-off the hole.

I'll post some pics of my setup tomorrow - I discovered I didn't take any pics of the job I did!