The A500+ are Rev8a motherboards if I remember correctly... different Agnus socket + pin arrangements compared to a normal A500.
I would just replace every green socket or surface soldered chip as possible. Resisters will be available from electronics places, IC's from a standard A500 should swap. Solder in your new sockets and jumper any corroded tracks if able. See if you can bring it back from the dead
Amiga's are much nicer with 2meg chip ram!