one other thing to mention.
if you are special ordering this alt, consider the m-body alt instead.
every parts store carries it and it is 78amps.
it will be a square back so if original looking is more important disregard.
but if ease of getting it replaced if it fails is, then consider that instead.
I have never mounted one to a BB, but on a SB you need a longer swing arm and the 10 dollar chrome GM one that all parts stores seem to carry works with spacers to bring it out far enough away from the block to match up with the alt.
That is what I used when I converted my 51 Plymouth from 6v to 12v.
Running and electric fan, a good one, is the only real addition to the electrical system, right now. EFI is coming though.
