LS6 fan belts

[Mr70]

Hi John,how's your Summer going?
Sounds like you want a Big Block 1970 Alternator belt AND w/o SMOG too,as it wraps around just the crank,water pump and alternator pulley only.Original Part# for that is #3937789 & can be used on ALL 1970 LS-3,L-34,LS-5,L-78,LS-6 applications W/O SMOG.
Quanta sells this GM Restoration/factory correct looking belt as Part# 29B-602,but cross reference with other MFRs.that might have a different look.And I recommend whomever you buy from,call and ask them to confirm the overall length with you first before ordering,as they measure out at just over 46 inches with Deepgroove pulleys when on the car,(at least mine do when stretched.)
Anything longer is a Big Block SMOG PUMP (YE) Belt.

And Power Steering as you know is a separate belt run by the crank pulley only,and not powered by the Alt. belt.