The teflon 8-71 is going to be tough on the street. It probably wont make the boost u are looking for in a 540 8.5 to 1 engine. Spinning it faster is going to make the intake air temp rise more than the boost you will get out of it. The bigger blower is better, You wont have to spin it as fast which is better for the end of that bbc crank with no support. Dont get me wrong a 14-71 is gonna be a big momma to spin, but it will make any boost resonably could want and have a lower air temp on the charge.
Back to work!!! At least its Friday