I am not sure what you mean by "the electrical system going is the start system", the ignition has to be running to make the charging work. I also am not familiar with the 1 wire alternator system. All of the alternators I know of have at least 2 wires connected 1 from ignition via the light to feed the field and an output to the battery.

Tony 

FWIW I have one wire alternators on both the 38 and 53 (the 53 has been converted to 12v). To minimize the changes necessary I simply taped up the Field and Armature wires and ran a single heavy wire from the alternator terminal to the BAT terminal on the voltage regulator leaving all other wires connected normally. If you change to a one wire alternator be sure to buy one that excites at low RPM.

Looking to find a shorter belt, Gates 25-22397 is the for the gen. Alternator needs a bit shorter .

An inch in length makes a big difference on the car. If the existing is just a bit too long buy an inch shorter. Most FLAPS will let you bring it back for exchange if it doesn't fit. Make sure you keep your receipt. You will likely also need to buy a mounting bracket. Generator and alternator brackets are not the same. While not inexpensive they are available from most vendors.

 Filling station sold me the alternator & mounting bracket. They don't show a shorter belt.I think the old belt will work but I want to tuck it in a little. 

I got a shorter belt & will try Tuesday.