Big compression engines with big cams run tighter than the general rule of .080. They sometimes leave a witness mark on the pistons. IMO .040 to .050 will be fine with that cam as it probably won't see 7,000. Was the clay checked at zero lash? If so .020 on the lash makes it .038 right?
On the intake valves .050 at the closest will work fine with good parts and don't float the valves, .060+ on the exhaust with good valves and springs, rockers and pushrods work well also
I've had them close enough that there was no carbon on the piston tops under the valves and I couldn't feel any contact on the pistons or valves and none of the valves where bent
It's not that I am recommending that though
