The reason why they say not to use the coil or the alternator is that for one if you use the coil, the draw from the choke heater (which is constant) can lower voltage to the coil. As far as the alternator, you need a terminal that is getting charging voltage only when the engine is running to avoid a choke that opens too fast. I actually called Arco marine when I was trying to do a Holley conversion (wound up going back to the Q-Jet with the divorced choke) and they said that the diodes in the alt might not hold up to the current draw of the choke heater, and suggested using a relay, so that the alt only triggers the relay which is powered off the battery common terminal on the battery switch.
I used to have that old style OMC alternator (Motorola I think) and there may be a way to do it...because OMC used the Holley on the Ford 460 in the same year range as the engine you have. The chokes are the same more or less from Holley to Edelbrock. On the Motorola alt, there are 4 terminals, one is the B+ (large orange terminal) one is the AC tap (directly opposite it) and the 2 others are the Excite and Sense terminals. The Excite should have the purple red wire hooked up to it, the Sense has the purple wire hooked up to it. Try running it and see which terminal gets at least 12V with the engine running only. If you don't have that alternator, post up what you have. In the OMC wiring harness for the Ford/Holley engines, the choke was connected to the AC tap terminal on the Motorola.
If you don't have the Motorola (which sounds like what you are saying) post up a pic of what you have.
