Well we gave it the old college try But looking at your pics again and got me thinking is your ram going to fit with the 120mm there anyway?
Is this a hot running system? Could you get away with using the 240mm by itself?
Seriously I'd drain it and take it to my local Automotive Radiator repair shop and have them fix it properly.
I've done this to several rads now with great success, the only downside is repainting them after the repair .
Gotta love aussie thinking Ifyou want an easier/simpler mounting use a 38mm fan body as I've done to the rear of my TJO8-E server
also allows the inside mounting of the other 25mm fan = neat and tidy
You can lift the case with the rad although not a regular thing.
Where in Oz are you located?