This time of year there is a lot of that stuff for sale on the boards. Rexone sells that stuff also. He has an online catalog.
There was couple of V drives in the used thread also if they are still there.
Blown alcohol 496 with an 8/71 and speed? Depends on the boat, tuneup and how well it is set up.
I'll put it to you like this. More power than they will let you legally run in an open boat. 120's anyway.