I installed a set of the 37/42mm grooved venturis on my '67 and I'm pretty pleased with the results so far. I had to go way up on the air correctors and I'm still dialing it in but it's getting close. The engine seems to have a much wider powerband now.
What size/spec is your engine?
It's a 2332 with 44x37 Jeff Denham heads, 9.5 to 1 compression, the cam is Web cam with .498 lift and 312 duration, 48 IDA's, 1.75" merged exhaust.