a 1 in 9" twist will not likely stablize a heavier bullet. In fact your rifle will probably shoot 55 grainers well enough... Having said that, you could try something a little heavier but I wouldn't expect any miracles.
I have a Tikka with 1 in 8" and while I've tried some heavier bullets up to 62 grains I found out quickly that they wouldn't group as well as I wanted them to group. Oddly, the winchester 55 grainers were so accurate I didn't search for anything else and still use them today.
I don't consider the 223 as a primary deer cartridge, but it could do the job if I really needed it to. However if you consider stepping up to a 243 in a 100 grainer, then you've got it made for deer and wolf.
The main issue with a lighter cartridge is getting one's shot in a vital place to bring down larger game. With a coyote, a 223 is more then adequate tho...