Suggestions for non-Magnum 360 that started running badly?

I have thrown some parts at it over the past year, thinking that it might be electrical: MSD cap and rotor, Accel wires and new plugs. The only other spark issue I'd like to check before focusing completely on engine vacuum is the reluctor gap in the Mopar EI distributor. Now I'm an amateur mechanic, and am finding this pretty hard to do because the distributor is at the back of the block and the reluctor is toward the rear of the distributor, pretty close to the firewall. Have any of you guys figured out a way to more easily measure the reluctor gap on the LA small block?