Brian,
Look at my Derivative thread in regular Pattern, Originally the model was set-up on a piped and soft mounted DLE55. It turned a Mej 20x12 3 blader and had terrific manners and sound. Didn't measure it actually but I would guess noise to be around 95dB at 3 meters. That's pretty quiet as gassies go but it also on the bottom of your displacement spec
The fuse was all composite with balsa sheeted foam wing/stab and that may have been a contributor to some noise. All balsa fuse with appropriate soft mount such as that shown in those photos would deaden noise even more. I'd stay away from built up wings and stabs with plastic coverings. I make soft mounts for all my gassies but have not made anything for an engine larger than 60cc. Good luck and if you need more specifics, contact me directly at my email....