What's the deal with Com Cams?

I've had hydro roller lifters on back order for months. (8920-16) They say they'll ship the 5th and then they say 11/15, 11/24 and the latest is 12/10. I've got all the other parts for this '74 small block including the cam, roller rockers, ect, but no roller lifters for months now. Any body know if there is a substitute hyro roller that will run on the comp cam i've got?