Bo.....Yeah.........you CAN get away with that arrow choice, but its not ideal. It' s actually a lot less than most people use for Whitetails. I' d personally like my arrows to carry a little more momentum into such a big animal so I' d up the weight at least 25-50grs and give up a bit of speed. ( If you had a 60-70# model and were shooting at least 65# we wouldn' t be having this conversation. )
Look at it this way tho........for 61# and 28" you are doing about as good as it gets energy wise!
My 374gr arrow will do 319fps out of my bow, and a 474gr at 289fps (leeches,peep,loop).... so I' m kinda workin' backwards here!

Your case is one of those where I' m kinda goin' .........well.............yeah.........but........ ..ahhhhhhhh.............
Not quite sure what to recommend.

But I' ll give it a whirl . With your set-up not changing the bow at all,You CAN obviously kill an elk with it BUT I' d rather.........410-415ish gr arrow,260' s speed, solid fixed blade broadhead.........Montec,Magnus, Wasp Hammer SST, Rocky Ti.
Any more weight you will start to fall off the table at longer ranges, any lighter and you are risking penetration problems.
Use vanes instead of feathers also, they will drag less and you' ll maintain more velocity at 30-50 yards if you need to shoot that far. If you don' t want to spring for new arrows, If you fletch with (3) 4" vanes and some nice cresting wraps ,depending on how you have your arrows set-up now, you could pick up an additional 20+ grs?

If you are going to stick with that original light arrow I' d consider more along the lines of the 2 blade Magnus style head to MAXIMIZE penetration.