Absolutely it could held with straps, anything can be done, but you will need a lot of attachment points to prevent movement which is what you want if you are doing any task that requires imparting any amount of force to accomplish. Suspending a motorcycle from the legs of an automobile lift is not the same as mechanically lifting a motorcycle using an automobile lift. If you are going to be working on an 800 Lb. motorcycle that is suspended from the air you don't want to be around it with it suspended from normal tie-down straps let alone working on it. I know I wouldn't. I would only use properly rated lifting slings that are designed for continuous load suspension. Even with that you should never be close to or underneath a suspended load for any length of time while it is suspended let alone working on it. Even if you have proper slings to minimize the risk you then have all of the stabilization straps that you are using to attempt to keep it where you want it that will be in your way when you are working on the motorcycle. After having done all of that it still won't be as stable or safe as it would be sitting on a lift table.
I am not suggesting that this can't be done, of course it can. If it is the only option available go ahead and use what you have but set it up so that it safe for you to be around it, which is to mechanically lift it rather than suspend it. In my opinion it is not a good idea to be working on an 800 Lb. suspended load. A lift table is a better option if it is an option that is available. Once the motorcycle is on the lift table everything is accessible while it is much more secure, more safe, and much more stable even with both wheels removed at the same time.
