I don't think you'll hover with a .61. I would go for a .91. I have the Mag .91XLS, OS .91FX and Mag .91 4-stroke. Any of those would do. With the OS, you'll need to fix the needle valve. The Mag .91 4-stroke would be a good combo. If you get it, it's a ringed engine so break it in slobbering rich and add some extra castor to your fuel for the first 3 tanks or so. I kept mine to 4000 rpm or so for the first 2 tanks, then slowly increased and leaned out. The ring seated and the compression came up great.

With the XLS or OS, you can get the Ultra Thrust muffler for 800-900 more rpm.