Really! at the end of the day get a 5.7 and go nuts. The 6.4 is really a 5.7 same block . its a stroked 5.7. The 6.1 has many more options for doing lot of mods!
Wrong, 6.4 is not a 5.7. It has a standard bore of 4.09" with a 3.72" stroke. A 5.7 is like 3.96" bore with a 3.58 stroke. A 6.4 also has a forged crank and oil squiters just like a 6.1. 6.4 is a BAMF....