Thanks all for the input!
I think I will go for a compromise by just using alternate materials where I think it is critical and try to keep as close to the original plan as possible.
I like what I am reading about paulownia wood and I think I will try to use it in critical areas to increase strength. Spruce does not respond well to CA. I think it is some oils that hinder curing of the CA. I am hoping the paulownia will respond to CA better.
In the current fuse and tail parts I am using some spruce and I will weigh the finished assembly to see what the impact was. Next week when the paulownia comes I will build an assembly with it but because it is so light I may go for building mostly if not all from it.
As far as scale flight goes it has always been interesting to me how scale effects are not linear. I learned to fly a full scale Aeronca Champ. If I use that plane as an example it weighs about 850 lbs. and has a Vmax of about 100 mph.
So, if I built a 1/8 scale champ it should weigh about 100 lbs. but cruise at about 12 mph. Pretty crazy. A 1/8th scale champ that weighs even 5 lbs. will likely fly way to fast to appear scale due to high wing loading. The ultra light electric planes really do look scale on a really calm day but add a 5-7mph wind and they look quite un-scale due to the response to turbulence.
Anyway with my current fleet of 2 scale planes I only use full throttle on some takeoffs and rarely fly over 1/3 throttle in full flight.
Maybe I can find a happy medium at about 27-30 oz. for a 53" span.....