[Jamesp]

If you're not already done, locking the crank at zero degrees is what is important because that unloads all of the valve springs so the cannot physically push the cams to change the valve timing. Locking the cams with the cam locking tool is not necessary for an IMSB replacement. The durametric is giving you valve deviation while running, which is all about the chain ramps, chain tensioners, and timing chain stretch. There are quite a few threads on adjusting the cams to try to compensate for the deviation due to wear.