I have done a lot of these conversions and use an internally regulator GM
alternator. Use whatever pulley comes on the alternator. It will charge at at
full output at about 1,500 engine rpms, maybe 3,000 rpms for the alternator. Be
sure to bypass the stock regulator. The voltage output will be the same as the
generator which is too low. Use 6 or 8 gauge wire from the alternator to the
battery or lug on the starter solenoid. I personally like to reduce the speed
for my water pump and alternator to save on gas. My water pump spins at half the
factory speed and I get increased cooling. The alternator pulley size can be
increased a little, because the old 6 spins fairly fast on the highway. I would
guess from prior experience that you need to keep the alternator spinning above
2,500 rpms to get maximum output. On the other hand, these old sixes idle much
lower than a regular engine. But for 25 bucks for an alternator with a pulley on
it, I would just run the alternator as it comes out of the box. Don't go
"cheapskate" and reuse the original wires. They are are not even close to being
adequate for an alternator
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