Good motors if never overboosted. Came a little rich from the factory.
Run a compression check (or better yet, a leakdown). Look to see of you can tell if the heads have ever been off (broken paint on head bolts or repainted headbolts).
A stock 200 hour 525 should NOT have needed the heads off unless it blew a headgasket (lean mix, too much timing, low octane fuel, or too much boost).
Easy hopups are adding an intercooler and upping the boost to 6#.