The I20 pole is 12 ft and it is sheeted right at the stay wire. I would sell the spin and buy the "class" spin at 350 ft^2 the I20 is only 271 ft^2 I have not seen a Portsmouth adjustment for a smaller spin although a larger one will get an protest if not modified.
The 6.0 is a great distance boat and the 350 spin is great fun, I sailed it on my I20 and it was a hoot.