Kinda depends on your budget, future plans for the car, how you intend to use it......
If you're on a tight budget, and need the car for a daily driver, then drop in the lower milage motor. if you're sure it runs well.
If you plan on keeping this car forever, week end driving, going to the race track and car shows, then get a nice crate motor and drop it in.
'87 GT with a battery