150 HP LA 318 - vs - 230 HP Magnum 318

91 5.2 is a Magnum and was rated 235 HP with the "large exit" Magnum manifolds.

Rating went down to 230 with smaller outlet manifolds.

5.9 was rated 245 HP and was the same as the first gen "crate" 360, rated at 300 gross HP.
Just a note - first year of the 5.2 magnum was '92. '93 for the 5.9 magnum.