Put the back tire on a 4x4 block so you can lower the motor far enough to do everything. Get a compression tester hose to pump air into the cylinder to keep the valves from falling while you have the spring off
Might want to add using the new nylon rope trick to hold up the valve when working on the valve spring as a good cheap option. A wooden block under the back tire helped me. Also, label & baggie everything. If you do go the compressed air route, use anti-seize on the threads.