I recently did a Fluidyne.
1. Get the temp switch listed on Sean Korb's website. It's made for a Jeep or something like that. It fits perfectly, and it controls the fans perfectly. Put it in the "out" tank. Plug the other temp switch hole.
2. Do NOT mount fans with those plastic things that go through the fins. They will probably cause a leak. I attached angle aluminum to the radiator (pop rivets), then attached the fans to the angle.
3. I did mine in the stand-up position with sucker fans that are thicker than the flex-a-lite fans. The biggest problem was running the pipes. They rub the the fan on the lower right. You could make this easier by mounting the fans as far to the left as possible. That may not be good Karma, but you'll probably never see it anyway.
3. I doubt there's any cooling difference between lay down and stand up. I went stand up because I want to mount my A/C condensor in front, and I wanted more room in the front of the radiator.
4. The nipples on the radiator are 1.5". The Pantera pipes are 1 3/8" (or thereabouts). I used 1 3/8" elbows to hook up my pipes. You have to heat 'em up in hot water, plus lubricate them with radiator fluid, but they do fit. 1.5" hoses will fit too, but they are a loose fit on the pipes.
I've had mine for about 3 months now. I haven't seen the temp gauge go over 195deg.