What would the HR's numbers be previous to the new SAE standards?
 

DE and DE re up numbers (before the new SAE standard):

03-05 DE = 287/274

06 DE = 300/260

07-08 HR = 306/268 (measured against the new standard)

My question is how much higher would the HR's numbers have been before the SAE stepped in?

I remember something about the non-revup DE would be 275hp under the new SAE standards, so I'd guess 320hp for the HR under the old standards...

Anywhere from 313 to ~321

327 hp Gross , 309 hp Net in the middle east.

For reference, would you happen to have a source for these numbers?

500hp with the old standard

Here you go :
http://img148.imageshack.us/img148/6203/327hp.png