You glue them in there with the horse shoe clip in place.Then assemble like many other flathead engines.
Install lifters first then the rest.Retainer springs vsi spacers valve.The spring needs a little coaxing but not that bad.I also shorten the guide to 2" after the liner install to make the assembly a little easier.Not much of a deal.You will need a valve spring compressor to complete.With the compressor you have free hands to work with.You can put pos seals on the machined guides as well.Take care when installing springs when seals are in place,but quite doable.This is all done before the valve job to aid in keeping all with a minimum runout.Once the guides are glued in the valve job is completed and then assembly can be resumed. Hope this helps you along. I'm sure there would be more loctite products that will work.That is some that I have on hand.
Just2¢ more.
R