Radiused or flat fingerboard?
The radiused fingerboard has been around the acoustic and the electric guitar since day one. The same is true for most instruments of the Stringed family of instruments (violas, violins cellos, bass). Radiusing (image above) makes barre and left hand stopping A LOT easier. The only drawback is that you will NEVER want to play a  flat fingerboard after that. If you are having your custom guitar built, I am all pro radiusing the fingerboard.  The standard fingerboard is flat.
 
 

The fan brace is based on the Hauser 1943 Frame. It incorporates 4 different species of wood: Sinker redwood, Spruce, Cedar and Mahogany. The sinker Redwood is the transversal strut that shortens the trebles side to augment the power of the high registers whilst Cedar and spruce were used on the bass side to augment the power of and resonance of the bass line. I think I can affirm that she has the most powerful 6th string I have ever heard and one of the best ringing trebles you can hope for. Simply amazing. The top was reduced to less than 1 mm towards the edges and just a little over 1 mm towards the bridge area where I installed a new underbridge system that connects the bridge with each strut in the fan brace whilst directing each frequency to the right portion of the top.

650 mm or 640 mm?
Keep the following rule at hand: If the distance between the tip of your thumb and the tip of your little finger is equal or less than 9 in. when fully stretched, use 640 mm. In stringed instrument performance, a single millimeter can mean the difference between playing effortlessly or the exact opposite.