I have a 12" pusher fan on my Wes Ingram radiator and I did not have to make big changes to get it in. The only downside is finding a suitable top hose for a Spider. Conedriver found one in a very helpful auto parts store. I used a piece of wire reinforced, general purpose flexible hose. I can post a picture if you decide to go that way. Maybe my 190 HP motor is generating more heat than most. Connecting up the oil cooler made a big difference.
76 Suzuki GT500
2011 Jaguar XKR
A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke