4 decade old springs = bad idea. Even if they've never run, they've been under load for 40 years.

These will drop in and give enough load for whatever you're likely to run w/ stock heads.

Their #1105 spring would probably do well for a lot of applications, too.

When the springs are off, just make sure that the retainers won't smack the tops of the guides. That's NOT a good thing



-Bill