Recently purchased used Sunline

Hey all, I recently purchased a 79 Sunline model TL. Just returned from my 2nd camping trip but this was the first time I've had access to electric and water. I had noticed the toilet, an Aqua Magic III, seemed to be missing something but, being a 1st time rv owner, I wasn't really sure. After hooking up the water at the camp grounds, I found that water was spraying from the area that appeared to be missing something, which did in fact, confirm that something was missing. After a little research, I found that the flush handle is gone so I need to find out if this part is replaceable and where I could find it or if I just need to replace the whole toilet?

I would also like to replace the shut off valves for the holding tanks as the seem to be a little worn and hard to open and close.

Any help would be greatly appreciated.