Not sure what motor you are proposing. I find 16oz a pretty light setup but that is not my point. Pay attention to what Dave Rigotti said. Acceptable wing loading is in the 11-13 oz range. 15 can be trimmed to fly well if you have a good motor. What you are targeting is closer to 17-18. When I build my target weight is always 13oz @ sqft. Is there any way can lighten the load? When that size plane was the "state of the art", they weighed in around 28-35 oz dry, certainly under 40. I know it is probably too late to do much but if it is not finished - think light!
I flew an enlarged (510 vs 490 sq") Sig Twister for practice for a couple of years. It weighed 52 oz WITH a 2800 4s battery and a Cobra 2820/12 motor. That is a wing loading of 15 and it flew like it was heavy, but it did fly well.
Ken