I believe confidence in your equiptment is paramount. If your set up is quiet and you acheive good arrow flight, no wobbles or flyiers, you are leathal as long as your arrow is flying. I have a 66 inch JD Berry Vixen longbow that shoots my 580 grain wood shafts like they were carbons, absolutely straight. I think it shoots slow as it is like 50 pounds at my draw. That is like 11.6 gpp of draw. I think it may be about 160 fps or so. No matter, I am confident it is big medicine for any white tail deer I may encounter. You will have better FOC than I do ... you should have a very nice set up there.
Bob.