Advice on potential gear swap

If you only drive casual street and are concerned about gas mileage, then the ratio's you've selected are good. If you are unconcerned about stoplight acceleration, then those ratio's are good. I was there when these cars were new and gear sets were poor. We did many rebuilds. So I would not be in favor of buying any NOS gears. I would buy from Yukon. 3.23 gears are a popular compromise.