pulled codes, please help

[84LX89GT]

god i hate EVP sensors, had constant problems with EVP signal in the 89 GT i had only to find out there was high resistance in the signal wire from the connector to the pcm somewhere hidden far away.
-the EVP sensor, or E.G.R. valve position sensor is a sensor with a plunger than mounts to the egr valve and sends varying voltage depending on the position of the egr valve. Chances are you have a bad EVP sensor or faulty wiring make sure there's no corrosion in the connector.

67 neutral circuit failure - don't worry about it especially with an engine swap unless you feel like doing more wiring if it's not already installed.

29 see what happens with new gear, you may have a bad vss sensor or wiring

56 either the mass air flow sensor is faulty or you have a wiring problem. It sounds like either the MAF sensor is bad or there's a wire shorted to power or miswired.