Not sure if they really changed much over the years.

These engines are famous for the heads cracking between the valves. Not sure if there are certain years of heads that are less prone to cracking?

Other stuff I can recall reading on here over the years:

No provision for a mechanical fuel pump.

Valve covers are double ugly (imo) and while older LA covers do fit the magnum heads the gaskets don't have a lot of sealing surface on the ends.

The small ends of the rods are different width so certain aftermarket pistons don't fit on the stock magnum rods, iirc.

At one time adding a carbureted LA intake to a magnum meant you had to redrill/slot the intake bolt holes. I'd imagine you can just buy a carbureted 5.9 intake that works by now.