im shooting a Highlander with an IBO of 305fps set at 28" draw at 67lbs. 378gr arrow(5.64gr/lb) which is a kinda light hunting arrow..i think they say 5.5gp per lb as being the base line for safe(could be wrong) and am shooting that setup at about 260fps.

a 300gr arrow IMO is kinda light for hunting purposes...400 is better..your probably looking at 230-250 fps give or take a few..if this is a hunting bow i wouldnt worry about speed. pick the bow that feels good to you. dont worry about the speed. put the arrow where it needs to be and your draggin a deer.

at 300grs and 240fps your looking at 38ft/lbs of KE..
at 400 and say 230 fps your looking at 47ft/lbs
450 at 225fps your looking at 50ft/lbs
500 at 220fps your looking at close to 54ft/lbs

so you can see why i like a little heavier arrow rather than pure speed. i rather give up a little speed(fractions of a second when your talking hunting distances) to gain a good bit of KE.

in the end its your decision...put the arrow where it needs to be and your draggin. thats the most important part. good luck...