THe old 284 is a great round. I chamber more specialty handguns for this chambering then rifles but it makes a great rifle as well. You really do not need alot of twist. Some prefer a 1-8 for the 175-180 gr class bullets but in most cases a 1-9 will handle them easily.
I personally feel the bullets over the 162-168 gr range are a bit heavy for this class of chambering simply because the lighter bullets, at least the ones with the better BC values such as the A-Max and Berger VLD will do very well with the velocity advantage they have over the heavier bullets.
Basically put, whatever the 280 Rem will do, the 284 will also do, or at least be so close that it would be impossible to really tell them apart down range.
Its a great chambering, but the main reason its still with us because of its wildcat offspring.