Was planning on it, any info as to why that's a bad idea would be appreciated.
The generator is not know for a very stable voltage output.
If you can tweak the regulator to maintain a constant 13.8-14.2 volts at the battery then you should be fine. O zero out the voltage compensation table in the ECM's program so it won't compensate when the voltage drifts.
The 10 and 12SI is better if set up properly. Use the info at www.madelectrical.com
for those. Read about the proper setup of the sense wire.
The newer CS series of GM alternator was designed for the newer EFI systems with a much cleaner voltage out. They can be a direct swap for the SI series.
So the CS is the preferred. The standard is a CS130 so there is plenty of amps there to play most any accy.