340 xhead spring shimming, height and pocket question(s)

What I found out from comp was, the spring rate has to be high enough for a more aggressive cam. Prevent valve float at higher rpm, your running solid lifters. Lighter then recommended springs could through your valves a bit. Depends on what rpm’s your going to be using. Some of the old racers I heard used to set up the valves that way to get extra lift in the stock class