1. You have a hydraulic cam. You don't have "valve lash", you have "lifter plunger preload", or "Lifter preload".
2. With compression numbers like you're getting, I don't know how the lifter preload could be too tight.
OTOH, checking preload is simple; although a bit messy if the engine is running. Used to be a guy could cut the top off of a scrap (perimeter-bolt) valve cover, and use that to hold the oil in. But since Chevy switched to four bolts along the top of the cover, cutting the valve cover got a lot harder.
2. With compression numbers like you're getting, I don't know how the lifter preload could be too tight.
OTOH, checking preload is simple; although a bit messy if the engine is running. Used to be a guy could cut the top off of a scrap (perimeter-bolt) valve cover, and use that to hold the oil in. But since Chevy switched to four bolts along the top of the cover, cutting the valve cover got a lot harder.