Many, including myself, will argue that the 1989 HO 5.0 engine was the best
of the lot.
It has roller rockers, forged pistons, and lots of other good stuff. Many have
over 200,000 miles on their stock engines with only normal maintenance.
The 5.0's are also very easy to work with, and horsepower per dollar is much
cheaper than the newer 4.6L modular engines. My 1989 LX stang was running
13.54 with only headers, a 3.73 Detroit Locker rear, and suspension work.
The engine was completely stock. The car is now running low 12's N/A with
only bolt on's (heads, cam, intake, etc.)..
Good luck with the car, you have a good one there..