I had a big issue with needing a good amount of amps at idle.

I currently run a 8mm cog system with GM 100amp unit over driven 2:1 with a 8mm cog pulley from these guys http://productengr.com/alternators.htm
and a BDS blower pulley cut down to 0.75 wide for the crank and a low mount bracket from Jegs for a BBC....Works very well even with a 100amp alternator.

See attached pic

3079996-hemi587.JPG (504 downloads)
'70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car)
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

'66 Barracuda AWB Stretched nose Blown 440 Car in build stage

'71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph
https://www.youtube.com/watch?v=Znuo3jMUXTk