I just rebuilt my 1965, 289 and installed 1993 Cobra GT40 heads w/ Scorpion pedestal 1.6 roller rockers. I’m running a new Hydraulic Flat Tappet Camshaft (see cam card attached). My stock 289 pushrods are too short. So I bought an adjustable push rod to get the correct size... My question is, how do I know I have the correct lifter pre-load? I have installed the adjustable push rod and rockers on my assembled heads and adjusted to zero lash with out depressing the hydraulic lifter. I have also taken a sharpy pen to see the wear pattern. I can get the wear line it in the middle of the valve stem, but how do I know I have the correct pre-load on the lifter? I can lengthen the pushrod to were the lifter is partially depressed at zero lash and still get an acceptable pattern on the valve stem? Anyone running this combo or have a suggestion?