critique my 340 w2 combo please

Depends entirely on what rear tires you are planning on running. 4.10s will be 2.05:1, 4.30s will be 2.15:1, 4.56s would be 2.28:1, and 4.88s would be 2.44 in 6th. Drive line balance and fabrication becomes really critical when you start running it twice the rpm of the engine. Whole different world out there on the Montanabahn, though.