Pete
Sadly, the SCCA has been scared of the Porsche cars since the late fifties when "the Giant Killer" known as Bruce Jennings to the rest of the world, cleaned everyones clock with a 356 Carrera. Ever since then the club has tended to classify the Porsche cars at a disadvantage.
You would think that this would change somewhat in the modern era with the club looking for all the entry dollars it can get. Too bad, because the 86-89 911's were great cars and are raced in both PCA and the NASA GTS series.

Something to keep in mind though, with the economic downturn the ITE field at DC Region races is looking very small and some wins could be had without breaking the bank.
If you have any questions feel free to ask here or PM me.
cheers
dave parker