LD4B how good and how rare what are they worth?

Compares OK with the Air Gap/RPM. The port thing is a red herring. The manifold flat works well. Plenty have tested the 4b and a LD340 back to back and the difference is nill at the track.

Bad, no coil mounting bosses. Have to run a coil bracket similar to the 340-6 cars.

Values, usually 200+ for one in nice shape.