Woohoo my friend, you're in for a job. Have pulled several of those mechanical Bosch units off T6050/6030/TS-115 tractors.
Step 1. Disconnect battery. Seriously, you have to remove starter to locate engine. (13mm wrench)
Step 2. Remove the starter and fuel priming/lift pump. (17mm socket, 22 mm socket, 10mm socket) Removal of the priming pump is necessary to view the camshaft and determine if the engine is in the correct TDC position or 180* out.
Step 3. Rotate engine in its direction of travel (this is important, as it accounts for backlash in the timing gears) until the TDC pin hole lines up in flywheel/block. (You can use a pry-bar or large flat head screwdriver on the flywheel to turn it over, or go buy the factory tool for $$$.) If you go too far past, back up a substantial amount, and then come back to try again. This again accounts for gear backlash. The pin hole is at an angle. Slide a suitable pin through the hole and lock the engine in TDC position (you can go buy the factory tool, or use a correct diameter and length screwdriver/drill bit/pin that you have laying around the shop, the choice is yours).
Step 4. Inspect the camshaft through the priming pump access hole.
View attachment 455093
This is what you should see, if the camshaft looks otherwise, remove the lock pin and rotate the engine 360. Revisit step 3 to lock engine back down.
Step 5. Loosen the lock time bolt on pump (10mm socket on 1/4" drive ratchet!), remove the spacer tab, and tighten down bolt to lock pump. Keep track of the spacer tab. It's a small bolt, don't break it off Hercules, just snug it. (This isn't all that important if you're having your pump rebuilt, as a good pump shop will lock time it to spec when they give it back to you.)
Step 6. Remove all lines, linkages, and brackets necessary. Remove the pump flange bolts. (13mm socket and wrench)
Step 7. Remove the timing gear inspection cover off the backside of the engine, between the cab and engine.
Step 8. CAREFULLY break free the retaining nut (22 or 23mm socket) and remove the nut and lock washer WITHOUT dropping either into the crankcase! (I normally use a 1/4" sized extendable magnet stick to prevent me from screwing this up when removing/installing washer and nut. Stick the magnet on to the pump shaft and center it up, then unthread the nut and slide the nut and washer onto the magnet stick, keeping you from dropping them.)
Step 9. The pump is an interference fit into its timing gear. It has to be pushed/pulled apart. It is not keyed, although the pump shaft has a key way.
You'll either want to use the inspection cover as a template to make a pusher tool, or best yet, buy this tool from Snap-On, Amazon, EBay, etc.
Snap-on Store which bolts onto the timing gear and pushes the pump shaft out of the gear as you tighten.
I once made my own tool that bolted up using the inspection cover bolt threads and had a 1/2" bolt center lined with the shaft, so when I tightened the 1/2" bolt, it pushed the pump out of the gear.
Although it has been done, I don't advise hammering on the shaft with the nut screwed on flush, because you'll booger the shaft on a $2500 pump.
If done correct, when the pump shaft pops free and you remove the pump, the key way on the shaft should line up with a hash mark on the back of the pump.
Good luck. If you own this tractor, or one equipped with these pumps, you'll get used to doing this.