I haven't flown a Spad, but I scored 404 points in Classic at this year's VSC with the D-7. It takes some care to get it through the full pattern, but it will do it. A bit more power and lower altitude would have been a big help. I'll bet it works just fine here at sea level. Mine was built by Antone Kephart, powered by a McCoy 29 and flown on 59'x.012 solid lines. 9x6 topflite prop, 15% fuel. Silkspan covering, minimal finish.
Larry Rice, a few things to consider doing:
Use a built-up/hollow fuselage of about 5/8" thickness (1/2" cut out balsa or structure with 1/16" sheet sides) and lighten up the plywood on the front.
I am not familiar with your wing construction, but the original could be made both lighter and stronger with better structure.
Consider built-up tail surfaces. If you keep the tail end light, you can use a .25 for power and have an overall lighter model.
Oh, by the way, Antone's model captured the "Most Unusual" trophy at VSC. Thanks for the loan, Antone!