Good points, Tony! Part of the setup on the HEI distributors I modify is to machine away the entire original mounting flange, and fabricate a hold down fixture with a pinch bolt clamp. Then the position of the pump drive can be adjusted up or down for the best fit, ditto with the drive gear/camshaft fit.
I also check the centrifugal advance curve on my distributor tester, and make whatever changes are necessary to either the total advance or the spring rate. Using the stock distributor to trigger an electronic module is a good idea, as long as wear or wobble issues are dealt with first. If a 4-pin GM module is used, be sure and mount it on a BIG aluminum heat sink with a good ground. Those things ground the coil through the bare metal base plate, and the power transistors develop a lot of heat. Use dielectric grease between the module and the heat sink.
Jerry
