RC
If you have an older Bridgeport R8, it is unusual for the keyway pin to have survived! It is only a grubscrew that has been turned down and a second screw to lock it in position. It is usually wrecked by not tightening the collet or collet chuck enough and the peg gets broken off. The spindle needs a stripdown to replace it, so instead, for the collets, if needed, a "spanner" with three small tongues to fit into the collet slots is used to hold against the drawbar torque. The peg is not there to provide any driving torque, so you can get away without it and the problems of indexing the spindle.
My little Denford Novamill has a BT 30 spindle with pullstuds and a spring loaded retainer. To fit a new toolholder, I have rigged up a direct acting air cylinder to release it. There is a carousel toolchanger that came with the machine. It consists of a rotary air cylinder to swing the tools into position and a DC motor to index the six toolholders. For the small, uncomplicated, short runs that I use the machine for, manual change is simple and quick enough.
Ian
P.S. DesignCad can import DWG, DXF, IGES, WMF, HPGL and XYZ (?).