For me, I'd look for a later 90's year EVO dyna vs an early 90's for 2 reasons. They modified the frame for the later dynas to have more of a stepped seat, compared to a flatter seat area on the earlier frames, so the later frames / seats have more lumbar support. The later EVO's had all the upgrades done for the cases, heads , etc.. Besides replacing the stock INA cam bearing with a torrington one , they are really all set to go.

The inner primary cracks you heard about happened back in the day when folks were building big EVO motors and stuffing them in the dyna's. "Some" of them did crack and companies like Carlini offered a torque arm that bolted from the cam cover of the motor to the side of the tranny to stiffen up the engine to tranny area and keep it from twisting...