Hey Jim,
I decided to go with Reno Engine & Drivetrain for the install. The Roush 402SR is a carberated version of the 402R. I'm far from an expert, but it's my understanding that the SR version (someone said that it stands for "street rod") is designed to deliver higher torque earlier in the RPM range.
You pay a BIG price in overall HP at the high end, but supposedly the engine is much happier at idle and at lower revs. My goal was ultimate driveability + some get up and go...still has 425HP which should do the job
.
I found some info on the web that shows the differences between the 402R, 402SR, 427R, and 427SR.
402SR Aluminum 425 HP
402R Aluminum 515 HP
427SR Aluminum 450 HP
427R Aluminum 550 HP
I just put my deposit down last week and can't wait for delivery!!