Tsuba / European crossguard hybrid questions

So I wish to make a hybrid guard between a quince style tsuba and a more traditional European style cross guard, I was wondering what the dimensions should be (blade length is 23 5/8'', overall length is 32 3/4', thickness is 5.8 mm - 3 mm, material is 9260, and total weight is 2 lb 12 oz, just for reference). Any ideas or insight would be much appreciated!!!