I've used the duraspark type before with an MSD 6A, 6L and it works like a charm. Just buy a new one from from the autoparts store. You may need to get it recurved for optimal performanc but they usually work good right out of the box. You have to cut the connector off of the distributer and splice in the extra connector that comes with an MSD unit.
- Cut the black wire coming out of the distributer flush with the grommet (it is not used).
- Cut the orange and blue wires coming out of the distributer at the connector.
- Solder the orange distributer wire to the purple MSD connector wire.
- Solder the blue dist. wire to the green MSD connector wire.
- Install the distributer and MSD unit and plug it in to the distributer.
I'm sorry but I forgot which year Duraspark distributer to ask for. Perhaps Backyard or someone else may know. Get one with the small silver vacuume advance. These are adjustable with an allen wrench through the vacuum hole. You should also pick up a later post style cap and rotor and the adapter for it. Where do you live? I may be interested in that 2.3, harnass, computer and transmission.