The guides will need to be measured with a hole guage and a micrometer
The hole guage I am referring to has a thumb-screw at the end you grab onto and it expands the end that fits in the guide, then you measure that with a mic.
I have gotten away with some pretty sloppy guides on some of my old junk. It would not be optimal for racing but with a new seal and no leaks or oil smoke, I guess I was lucky.
One engine I had in my 72 had a burned exhaust valve. I took one out of another head, stuffed it in the hole, (not too much play between the stem and guide) and twisted it to see if it made contact from the seat to valve face. Made a shiney thin ring on the valve face, installed a new seal and drove it for 2 more years
