Hard to say, but I've seen the 17x9 RPf1s on the tire rack site and was wondering the same thing.
Might be worth checking out Matt Andrews' blog:
http://fecompetition.wordpress.com/
He's been trying out 255s on his car with 6UL wheels from 949 racing.
I also think that member Scooby South on here has a similar setup.
Might work if the offset gods smile on you?