Hardened valve seats - do they really matter?

It came out to a measured 8.4:1 CR... Exactly textbook. I was hoping for more.
But it's together and running now, not coming back apart for the machine shop to have another shot at it. They took off what I told them to.

I hate to think what the actual CR was on that engine with all original parts as originally built.... I got it in pieces so couldn't measure. It was lacking the pistons and rods. I lucked out on finding a set of NOS rods for it for a too good of price to pass on from one of the "big racer guys" at the /6 site.

I do still have the original drool tube 74 head that hasn't been touched from new except for pulling it off of the engine. Never taken apart or machined.