need proffesional help on valvespring install

[Coupe50h]

I am trying to get correct installed heights on some comp cams springs, they are a single w/ damper "cca-942-16" to be installed at 1.7 height.
Problem is, I know the exhaust valve is setup for the rotator, which affects the installed height, and many people have had problems with rocker arm hitting the retainer ect, right now i have the stock retainers with rotators and the car ran fine, but am now going to buy the right 768 retainers and some shims, and also a height checker.
comp cams told me, after being on hold for 30 minutes, that i might need a different spring on the exhaust? to avoid using a bunch of shims?
I am trying to avoid that procedure, could anyone help me? i'll get the heights recorded as soon as possible, and maybe i can get them close to 1.7 with shims? will shims raise the height or shorten it? sorry for the dumb question.
thanx for any info.