That's complete B/S. My wife is 27.5"/45lbs/325IBO and she's fine for elk, you are far above that.
Not much downside to having an extra long arrow (I prefer to keep broadhead away from my hand too). You will find different opinions on this, but majority here (And myself) think a heavy arrow is best for elk due to retained momentum.
Easy to reverse engineer it: aim for arrow 450+ grs (which would get you 259 ft/sec and 67 lbs of energy which is great according to
http://backcountrybowhunting.com/calculator/). Figure out your arrow length (look at regs as mentioned), say a 26 inch arrow to make example easy. Looking at
day six's spine chart (my personal favorite) and that puts you at a 350 spine w/ 125gr head or just at 400 w/ 100 gr head. Just add up all the numbers (shaft length * gpi, insert/outsert, point, wrap, vanes, nock etc) and figure out what puts you where you want to go. Day six HD, black eagle, easton (injexions or fmjs), gold tip (kinetic, possibly pierce), etc all make heavy GPI arrows 9-11+ grains you'd need to hit that 450 mark.
Then use a cut on contact broadhead (expandables use far more energy) with less width (1 1/4" or less) and fairly swept blades + bleeders so you get really good penetration. Some great suggestions are slick trick vipertricks, rocky mountain cutthroat, day six evos, iron wills if you're spendy (and don't mind maintenance), etc.
You're done! Nice solid arrow with plenty of energy and penetration to kill an elk every day of the week. Put a good shot in the right area and enjoy!