I'm not so sure....
The blower that Toyota uses would be specifically chosen to suit their engine displacement. If your motor is 3 times the capacity, then I can't see that 2 of those blowers will do the trick. Yella Terra are making a larger capacity screw blower that might be more suitable.
Then again, if you don't mind some fabrication you could likely cut the Vortech price in half. I know of a brand new "Race" version V1 Vortech S-Trim (with the cog-pulley compatible heavy duty bearings) available for sale. I bought the blower into the country with my own V7 YS-Trim Vortech, and my friend only realised later on that
IT WON'T FIT THE ENGINE BAY OF A 911 PORSCHE!!!! 
Never mind the fact that he had all the critical dimensions two months before ordering the blower!!!
It cost him a little under $4K for the blower and bypass, but I can find out how much he'd be prepared to sell it for if you're interested.