When replacing only the piston rings, does the engine need to be broken in? It’s a 1985 lt50 with new piston rings cus of low compression?

When rings are replaced, the cylinder walls are roughed up intentionally to allow the walls to rub against the rings until both are smooth and exactly match their shape. If you push the engine too hard (and don't break it in gently) during this time, you could blow a piston ring (that is, move it out of place). Out of place, it might scar the cylinder wall.

When the piston rings get replaced the cylinders must be honed too. The main reason motors need to be broken in is for the rings to seal in the cylinders.

During the first 600 miles don't use synthetic oil.

Yes. Don't forget to run a hone over the glazed cylinder walls and remove the ridge at the top of the cylinder with a ridge reamer.

The bores should be honed, at a minimum, to help the rings bed in.

Then just run it - normal use will help bedding in.

However, If there is any trace of a wear step at the top of the bores, you must either use a stepped top ring or have that machined out, unless it's so slight that honing removes it.

Any step in the bore can cause new rings to break as they will have less wear and can travel slightly further than the old worn ones, so they hit the ridge and are damaged.

Yes