Buddy of mine built this 79 RR with 440 and 518 behind it . . .just used a switch to turn on/off OD . . . dropped the RPM by about 800RPM when turned on . . . was built long ago, and it had adapter for bellhousing to Big block and spacer on the crank to convertor. Think there used to be someone out there building those pieces . . . don't know much more than that . . .