Got me some NOS '69S heads! Valve guide question.
 

These heads have the original 1969 guides and have never been touched, but I am afraid that technology has passed them by. Should I use them as-is or should I replace them? Did the originals have a tendency to wear like the 2.7s did?

Use them!

So you might need to replace them in, say five years instaed of seven...if you do much more miles than most old cars these days..

Hrder guides are anyway a trade-off..

Kind regards
David

Use them as they are. Heat was the problem with the 2.7 guide as much as the material. The use manganese, silicon and beryllium has made the new guide material is better, but when ever you change a valve guide you risk miss aligning it to the seat. You can always recut the seat, but why?
As stated before most of these older car will never see 50k miles and the original guides will easily last that long.

Thanks Henry. Now I just need some cylinders. Keep me up to date.