As long as the arrows stay tuned to the bow. There will be no difference in group size.
If you increase the weight of the arrows or the grains per pound. The groups will hit lower on target.
If you decrease the weight of the arrows or grains per pound. The groups will hit higher on the target.
This will require the sights to be adjusted.

If you shoot the same shaft and increase the weight of the bow. It will decrease the spine. How much is hard to say but increasing the weight of the bow by 10 lbs will probably require the same shaft to be a bit shorter or a stiffer shaft.

You won't be making any significant changes in downrange energy by making minor changes to your set up, as is.
If your looking to get better arrow flight. Then some minor adjusting will work. The better the arrows fly. The better the downrange energy.

I practice with broad heads alot especially lately with the seasion about to start. I have no problem with flight and groups other than the 7 new fletchings I had to put on last night that had gotten cut from being hit. Those weights came after I did them.

Another thing that most dont factor in is FOC (foward of center). What that means is the location of the balance point with your arrow set up. On longer arrows it will be more to the center point of the arrow. On shorter arrows it will me more foward. When changing from feildtips to broadheads you are physicly changing your FOC because that broadhead is longer. Now at closer ranges this means very little if any difference, but you will see the difference at the longer ranges. As far as increasing your draw weight thats up to you and your comfort zone. One thing to remember is that you will most likely be shooting out of a tree stand and its a world of difference in pulling when you have sat there for hours stiffning up and then have to pull a bow. (Been there done that and it aint funny when you see a 10 point buck in front of you at 20 yards and you cant pull ya damn heavy draw bow back cuzz you have a sore shoulder) As far as spine, the terminator lite 6075 is fine for up to 75# at your draw length and its 9.1 grains per inch on the bare shaft if I remember correctly. If you did go up the 10 pounds you should get anywhere from 10 to 15 fps more out of it maybe more maybe less. Thats all according to your cams/cam

A 10-15 FPS increase I could really care less about. If anything I'd want more down range KE. Been shoot this setup for so long why change it, ya know. I may after the season up it to 70 or 75#. But not now with the season a week away. Be interesting to see how it effects things. As for the arrows the terminator lite's they are the new version of the terminator hunter's.
BTW sorry to hear about the big 10. Can't say I have had the honor of a 10 in front of me, well not while in season anyway. But I'm sure it musta tee'd ya off.

LoL Well I sure wasnt in the happy campers club Ill tell ya that... Tizz ok though... I tagged that sucker in Late muzzle loader that year.

Well how can ya get upset over that one. Just allowed him to add an extra pound or two in weight. Good deal.

If its penetration you are concerned with. Give the G5 Montechs a whirrel. I was having some penetration difficulties with my old thunderheads. I switched to them. Buck, 196 pounds field dressed, distance 32 yards, angle and point of entry, 32* up angle, 15* quartering away, 3/4 up body behind shoulder straight through inside lung and heart. Arrow ended up 7 inches into the ground after pass through. I think I solved me penetration problems huh!! LoL. Thats one thing I love about carbon and G5 combos. LiL hit with the rock and the G5 is ready to go, and with carbons, if it aint broke its straight! I have one combo thats been through 5 deer and still going strong. 65 pounds should provide PLENTY of KE at 30 yards. The main reason I balls to the wall all my bows is that thats maximum performance for one. And for 2 I dont have any worries about my tiller that way. Both limbs are walled out so equal. But with this shoulder injury I am most likely done for life with archery ( I just cant bring myself to call a crossbow "archery" ) I did get my bow back the other day but it hurt like hell and I know theres no way I could do it in a stand Another thing about the G5's, They will fly identical to your field tips. My bow pushes 305+ and I cut fletchings without changing a single thing. No broadhead tuning needed! I love that chit!!!