How to repair valve guide boss

If these bronze guides or even K-line inserts are new do not change them
just double check the clearance
as said above this procedure when used with solid bronze guides can crack the original cast iron- usually not a problem
if the clearance is off too loose or too tight then machine off the cast iron after you have new seals the right size for the bronze guide (after machining if necessary for size or retainer clearance)
I would knurl the new guides for oiling and refinish/ resize
I also od hone the valves- especially new ones as some have a finish that acts like a round file on your new guides- the hone helps holding oil and teh knurl supplies oil
welcome to unleaded gas