Back in the day we did everything in-house. I've done plenty of complete valve jobs on M102's, 103's, and 116/117's. The guides were checked for wear using a go/no-go gauge. If replacement was required we knocked them out the old fashioned way using a drift specifically made for the guides being replaced, and installed the new ones the same way. The only thing we didn't do was flatten a warped mating surface.

I wouldn't be surprised if you can find everything you need on Ebay............