I agree that an experienced and properly equipped shop would be best suited to do the job.
However, that being said, a lot of things are done to Bullets by the owners in the name of maintenance which will often work, even if not ideal. Sometimes this works out fine if the owner has some knowledge, and can execute a semi - decent job.
Vince is correct that a good shop can do a guide job and valve job fairly reasonably priced, and it can avoid headaches in some cases.
Our practice is to make any guide we need from our bronze guide stock on the lathe. This allows us to customize the fit to the head individually, and it often costs less than buying an OEM guide and having it shipped in. We have every size guide reamer imaginable, so no problem there.
But, we do Bullet heads all the time, and we are very experienced. Not every corner shop might be.
I would also recommend new stem seals when reassembling. Check the valve springs and retainers and collets for proper fit and for wear.
You can do it yourself, but learn what to do, and execute well, and be honest with yourself if you are getting in over your head with any of it.
In India, they just hammer these things into the head in the back yard, and go out and ride it to work. It's amazing how crude you can get away with on these bikes, but that doesn't mean that it is the right way to do things.