I'm not an aircraft designer, I've been just reading plans and copying things I've seen and read. But they have flown and we can figure this out. Here is an interesting page, it says::

"..This page is designed to give the measurements for a very basic model using non tapered wings..."

http://www.geistware.com/rcmodeling/model_calc.htm
Let's compare your numbers to what they say there. Enter the 34" span and 10" chord and choose barn door type ailerons, then click on compute. Then we can pick some of the numbers out of there play with:

Wing Span = 34 In.

Wing Chord = 10 In.

Vertical Fin Calculations

Vertical Fin Area = 45.33 sq. in.

Horizontal Stab Calculations

Horizontal Stab Area = 74.8 sq. in.

Horizontal Stab Chord = 4.99 in.

Horizontal Stab Span = 14.98"

Vertical Fin - Looking at your drawing on the tail parts I see the vertical fin as about 33 sq. in. as you have it drawn there now.

Horizontal Stab - The 6" x 14" hstab is about 84 sq. in.

So your numbers appear to be OK. But if you want to add 1" to the bottom length and 1" to the height on the vertical fin, making it 7" long and 7" high, that would increase the area to about 42 sq. in.

Your hstab is a little bigger but that is OK, leave it as you have it.

(I am using the calculator here to draw the parts and get those area numbers -

http://www.sketchandcalc.com/)

I'm confused about the number on the Fuselage Calculations. I think your number for the length are OK and I would just use what you have now.

Is this helping? I'm getting smarter too....

Jack