At 75# though you shold increase the weight of the arrow to at least 375 grains. But of course now you are back to pretty close to 300 ft/sec but with more of both ke and momentum. See what I mean?
No, I'm not concerned with meeting manufacturer weight recommendations in this example.
The 300 grain arrow at 300 fps would have 60 ft/lbs of KE, just like in your example. I'm going to increase it by 17%, which would require shooting the same arrow 325 fps. Regardless of what draw weight is required, will it deflect equally when compared to a 600 grain arrow shot at 230 fps when entering flesh, hide and bone. I believe the lighter arrow in this example will deflect more. It will have the same KE as the heavier arrow, but it's momentum will be less. It's energy will be diverted off it's path more easily.