RE: Scratch built ??
Here's the best info I could dig up, slowstang. The info was taken from an old "Design and build your own r/c aircraft" authored by Kenneth L. Smith. I have built several with the info from this publication and they all flew well.
Wing area 140 - 250 sq in. is in the .049 engine range.
There is no info for a wing in the 100 sg in. range, but suggests a weight of 20 oz. for a wing of 250 sq in.. Wing loading on this 250 sq in. wing carrying a weight of 20 oz. is 11.5 0z/sq ft. for a high wing rainer. A200 sq/in wing carrying 20 oz. will have a wing loading of 14 oz sq/ft, this figure is for a shoulder wing sport.
6-8 degrees total dihedral for a high wing 3 channel trainer is recommended.
I am just guessing here, but 8 oz. all up weight should be good.
Your dimensions look good, but I can't really be sure from the pictures. Good luck and remember: the first one is only a stepping stone to a really great flying model.