Well I've sent an email to GFS to see if they can recommend the best option for me.
In the meantime while searching mods to PAF Pros I stumbled upon this thread on Jemsite:
http://www.jemsite.com/forums/f35/pa...wap-72385.html
I read it, and thought why not give it a go. I have a set of old INF pickups, and one of them has a ceramic magnet.
Silly me though managed to pull apart the wrong pickup and replace an alnico 5 magnet with another alnico 5 magnet!

Imagine my surprise when I plugged in my guitar, and heard the exact same tone and gain!
After dinner I had another go, and managed to put in the ceramic one. Well plugged in the guitar, and there is definitely a difference.
The pickup seems to be pushing the amp a little harder, although still not as much as I would like. I think I need a stronger ceramic magnet. Can anyone tell me where I could buy a ceramic magnet for pickups? I'm having no luck finding anywhere so far.
The tone is also a little darker. Still sounds quite a bit like a stock PAF Pro, but definitely a little darker. That's good as far as I'm concerned.
I also noticed that when I switched from full humbucker to split coil with middle single that the output dropped a little and the tone thinned out a little. I'm guessing this is a result of the ceramic pickup.
It was an interesting exercise, and I definitely plan on getting myself a stronger magnet to see if the pickup will then push my amp even harder.