Transmission shifts at high revs and wont go into overdrive?

Either the governor is stuck Or I'm more inclined to think you screwed up the T.V.cable when you did the engine swap. Governor shifts with no throttle pressure are usually 12 mph, 18 mph then about 28 mph. stepping on the gas pedal you get into the throttle valve( T.V.) making the trans shift later, the harder you accelerate the later the the trans shifts. Also check the modulator or modulator vacuum line