RHS heads with 1.44" O.D. valvespring?

Glad to help.
Strange that your heads are machined differently. For what it's worth, I got mine direct from Comp Cams/RHS. Maybe one set through Summit.

I may try higher spring pressures with those same springs to insure the lifters stay on the cam lobes. 7,000 isn't a lot, but the cam has pretty steep ramps. Many Stock racers have seat pressures over 200 and open well over 400! Lots of unique things get done in this class.

Good luck!