Well, those are what's listed for a stock replacement '91 roller motor, so yeah they'll work- assuming you're using factory rockers.
Your motor is an LA block even though it's a roller, so it is drilled for rocker oiling. It's the Magnums that aren't drilled in later years.
Pushrods being drilled for oiling won't matter.
The only issue I see is the heads- '74s weren't designed for roller lifters, so the pushrod holes may (most likely will) cause some interference with the pushrods because they were located differently on roller motor heads to accommodate the different angles brought on by the taller roller lifters. You may need to have the holes clearanced to get the room you'll need.
