I purchased the Big Bingo plans from MRC and I just finished building the plane.  The wing I used balsa instead of plastic tubing for the leading edge and for the fuse I used lite ply back to the trailing edge and then hard balsa laminate to the ply.  Covered the plane with monokote.  I purchased a Satio 30 gas engine and I expect the  plane will come out below 16lbs.  The plane will be a test bed for this engine etc.  In the beginning i was going to use a G38, but weight bothered me a little with the lite ply construction and I figured that a Satio 30 ( Satio 180) would be ecomomical since the increase in glow fuel.  On utube there is a clip of a big Bingo with a US 41 that flies great.  So who knows the answer the to question what engine should be used on the Big Bingo!  Answer is comon sense.