You don't mention what your intended use is. My comments below relate to high power rifle competition.
The 1:7 twist was adopted by DoD because of the need to stabilize the long L110 tracer round out to 800 yards. A 1:8 twist will have no problems with either the 80 grain Matchking or some (all?) of the very low drag 80 grainers. You get your greatest return with those bullets at 500 yards and beyond, loaded long for maximum velocity (single loading for slow fire).
The favored bullets for short range (200-300 yards) are the 75 and 77 grain bullets, loaded to magazine length for rapid fire events. The 1:8 twist will handle them with no problem. I have a Colt with a 1:9 twist that does OK with the 75/77s, but others don't.
The 68-69 grain match bullets should all work fine with a 1:8 twist.
Lighter than that I don't shoot, such as the varmint bullets (50-63 grain). Theoretically the 1:8 is too fast for the lighter bullets and they'll take a hundred yards or more to "settle down." But I know guys using 1:8 match rifles who shoot the V-max bullets and are very pleased with the results.
To some degree, each rifle has it's own preferred bullets and loads.
