Turbo head build

9 psi over 2.06 inches is only 18 lbs. Dont think its going to affect your slant springs 62lbs closed sealing potential. Run any more boost than 9 and you'll need some more work elsewhere. If you got the springs already, go for it for peace of mind.
I did not say it was going to be a lot, just said the pressure on the back of the valve should be considered.