You can find these things out from RockShox web site. They have downloadable PDF manuals for most of their products. Now, granted, this is a service manual for an '
06 Recon U-turn but I will lay dollars to donuts that the numbers still hold true. On page 11 of this service manual is a rider weight/spring weight chart that will tell you which spring you would need to get that fork with.
http://www.sram.com/_media/techdocs/...ce%20Guide.pdf
Looks to me that you are definitely going to need the heaviest (black-stripe) spring they make for it, part no. 11.4310.139.000