273 adjustable rockers need refurbish.

If the new engine was completely rebuilt I would just run a light hone or some emery cloth thru the rockers, put them on new shafts, and run them. No need for grooves on a milder build that's fresh. Varying pushrod lengths are normal if the block was not blueprinted and the valve job was not done well. But givent he range of preload on most stock type lifters is generaous, get a length that will give adequate minimum preload on the shortest one, and that should be fine on any of the others.