Actually, good modern hybrid bows or recurve will exceed 150 fps at 14.5 gpp for 28" of draw length (Very best of them will be over 155 fps) and over 160 fps for 12 gpp (over 165 fps for the top the line).
When you look at the modern reports of buff killed with a trad bow, most of them were done with set up giving 160 to 170 fps for an arrow weight in the 750 to 900 gr. Some were done with lighter set up, some with heavier.
A modern top of the line hybrid bow 60# @ 28" shooting a 800 grain EFOC>25% arrow would be my "absolute minimum" (will give 160+ fps @ 28"), but with good release, perfect arrow flight and good shot placement. Must keep in mind that to raise this speed with the same arrow with an Howard Hill style bow and its 18 or 20 strand dacron string you will need around 85#@28 even or little more...
My hunting "go to" bow is a Fedora Xtreme hybrid LB 63# @ my 31" draw length, giving me a consistent 170-172 fps with 840 gr easton full metal jacket DG 5/16 " arrows for hog hunting. I wouldn't change anything in my set up for buff hunt and i am sure i would do the job.