[F-BIRD'88]

I would start by removing one spring and measure the real installed height of that spring. Then take the spring to a shop and heve them measure the real pressure at that height. And the open pressure at full lift. if it is in a acceptable range go with it.

To aid cam break in temp install stock SBC valve springs at 1.75" ++ (tall) installed height. (stock sbc retainers with no shims or oil cap.)
Reduced spring pressure.
Get them from a old junk stock SBC head. Reinstall the correct springs at the correct installed height once its all broke in.
For long cam/lifter life try to avoid more than 360# open or 140# seat pressure.
The installed height can be juggled with + or - .050" height locks and shims.

Anything around 100 to 125# seat and 290-350# open will work.
But its up to you the installer to check and verify correct spring specs.