Hi!
The HP .49 fourstrokes aren't that reliable and they are too big and powerful, and they are to heavy too.
A pair of OS 25 LA engines or OS .30 four strokes is what I would recommend.
I use a pair of OS FS.26 in my Marutaka DC-3 (span 211cm, weight 3,6kg )and these engines are perfect for it as they are very reliable and uses only 5% nitro and 15% all synthetic oil (Motul "Micro" ).