That SPR match is run by the same guys that put on the FDCC match in St. Augustine. The goal is to run those 3-4 times per year and down at the Volusia range we will have similar matches 3 times per year. To get the notifications for those matches follow FDCC on FB. I know they didn't post the first one on ARFCOM, but probably will from now on.
As far as what caliber, I always run my 308 in those matches and intend to also use the 6.5 Grendel I built. To me, the 308 is superior for the 400-600 yard stages, and though the 5.56 guns are usually quicker at the closer in stages, you are usually competing against heavier SPR type setups in this match, so that advantage is less. The 16" 308's with a 1-x optics was basically designed to do exactly what stages you find in these matches.