Hy Hellomrwilson, I'm not sure if different year 261s had different procedures, the following info came from a 1954 maintenance manual. The valve guides can be pressed out on an arbor press, they are pressed out from the spring side down through the combustion chamber, they use a shouldered tool to accomplish this. There are two different lengths of guide, the intake guides are longer than the exhaust guides. The guides should be pressed into the head from the spring side until the intakes are 1" above the spring seat, and the exhausts are 15/16" above the spring seat. Once installed ream the guides to .343 with a hand reamer, hope that helps.
