596 heads spring installed height too low

I run in problem. I bought comp cams 282 mechanical flat tapped camshaft and comps recommend 986-16 springs to use whit this cam. whit this spring it should to install to 1.750" and get 132lbs seat pressure.

Now i measure my heads and i get 1.650" install height. (whit my old locks and retainers, dont know them brand) Heads are machined to double springs and i have teflon type seals. Also have Crane roller 1.5 rocker arms.

I think i have to increase install height, am i right? If so, how i do it?? I have no idea. This is my first engine build..

Sorry bad english. Thanks.