If I read your post right,you've had a plane sitting for three years because your afraid to hand start it!!. There's a lot of electric starters on the market. I've been hand starting 150cc and bigger by hand for years with no problems. That ZDZ with the throttle set at idle won't backfire. By now your batteries may not be any good unless you've maintained them.
Get that plane out and fly it. It won't bite. Dennis