I wouldn't change any of the basics. Just lighten the plane where ever possible. Especially the tail. Move everything as far forward as possible.

My mods:

Mounted battery on an L bracket forward of firewall above engine
Moved servo tray forward
Used carbon fiber arrow shafts for control rods to rudder and elevator
Mount mini servos in wing for ailerons
Use mini servo for throttle mounted next to fuel tank
Solid metal landing gear
As large as engine that will fit.

I haven't flown mine in awhile, because the engine is about worn out. I'm sure it has over three hundred flights on it! I will never be a easy airplane to fly, but it is very fast and I always get compliments when someone sees it in action for the first time.

Keep us posted on your build, with pictuires of course!

Steve