I have shimmed more than one set of stock springs on both the RPM heads and Stealth heads to use them on cams with less than .600 net lift to get 140 to 160 lbs. on the seat sand between 325 to 375 lbs. open pressures. I shoot for at least .060 to coil bind also when I'm done with setting them up
I do have a older mechanical Rimac 1000 valve spring tester and a drawer full of valve spring shims so I use it and them to get all of the springs within 5 lbs. of each other on the seats
On your deal you should probably be able to get the same good results if you can find a shop that has both of those tools in stock