You let the machinist provide valves, guides and seats. New springs are a nice touch and not terribly expensive. You get what the machinist recommends. There are several choices of after market or OEM valves and guide materials. There are threads and surveys here on AdRdier dot Com that have more than a hundred posts and give well into the neighborhood of 3 dozen opinions on how to do this. Nobody is going to digest this and make any sense out of it. If you want to learn how to do BMW Airhead cylinder head work then I suggest you enroll in a BMW Service School. The tools for this work will run into the tens of thousands of dollars and the school will probably be a hundred thousand dollars. After 30 years of messing up other peoples machines I think you may get a refereral or two from some of the Inmates here.
It is not a list of parts and some pointers off the Web kinda thing. See?
Your part is called the R&R That is Removal and Replacement of the parts. To do this you need a pair of head gaskets, a pair of base gasket/shims and 4 push rod tube rubbers. You generally don't need things like new valve cover gaskets but when taking things apart you check these to make sure they don't need replacing.
To see if you might need rings, take the pistons off the rods, take the rings off the pistons and set them in the cylinders to check the ring gap. If rings are with in spec you can reuse them. The pistons can also be checked by putting into the cylinders with out their rings on and checking the fit with feeler gauges. Also wiggle the pistons inthe cylinders to see how well they fit and note weather the cylinder walls are worn in a taper. If you have trouble deciding if you need cylinder or piston ring work then a machinist can measure these things with accurate tools that most of us don't have.
You must be very careful when removing and replacing piston rings. These are not made to bend and they are easily broken. If you break one ring you will be buying all six too make things right. May in fact be what you need but it's still recommended you don't break the rings. There are special pliers for removing the rings and helping to not break them. I recommend using these tools instead of the finger nails which is usually what we do when we don't have the ring pliers.
You'll also need a suitable ring compressor tool to put the pistons and rings back into the cylinders.
If you are doing this much so far then also get the special triple square driver for removing and replacing the rod bolts and replace the big end rod bearings. These are not terribly expensive and are service type parts for our bikes. They get replaced merely because we are there.
You are going to need a suitable torque wrench for the rod bolts and the cylinder head bolts. The rod bolt toque is in your manual. If you still need it I'll look it up later. The cylinder head bolts are to be tightened to 25 ft/lbs in three stages. Use 25 ft/lbs as the final torque value and disregard any other toque value published anywhere.