Catalina Direct is a great resource for us, but not always the best source. Same with this place..they sell lots of stuff too.
If you have a standard rig, your "J" is 11.70 feet.
If you have a bowsprit, your "J" is 13.20 feet.
Poling a sail out to your "J" dimension is 'standard' procedure, so you would want to get a pole close to these dimensions, depending on which rig you have.
Any telescoping whisker pole will do. Forespar is pretty popular..I think you can buy them right here at SBO.
http://shop.sailboatowners.com/prod.php?14113
Be ready for a little sticker shock on shipping a pole..the telescoping kind are not as long as a fixed spinnaker pole, but anything long in a UPS truck pays a premium on shipping.