It's a Zorro slot card right? As I've understood it, in a 4000 the non v11 Busters have some issues with expansion cards.
Anyway, I and my assistant will research further.
Paws here have promised to supervise my restoration 
scan doubler goes in the video slot, buster doesn't affect it but the indivisions clip on top of the alice chip.Many old z3 cards would work on buster9(which supported multiple bus masters),depending on the card, but its best to run buster 11 for the most part.
the a4000 psu pinout can be found here:
http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/body_amiga_power_supplies.html#Fitting_a_new_PSU_to_an_A4000the molex connector is actually 6 pin.
