I had a Lunati Hyd Roller with their lifters in a street 440. Ran it 3 runs. Best of 13.30 at 4025 lbs with a bad converter.

I ran it to 6000 rpm and it did not go well. After the 3 runs half the adjusters were found to be loose due to valve float.

My 2 cents is be very careful if you run to 6000 rpm. Cover your ground very well. I used 10-40 oil and 10-30 would have been better. There are many variables including how quick the lifter can pump the oil, lifter weight, valve spring pressure, etc.

BTW - Lunati told me the cam and springs could handle 6200 rpm.