I dont know if you are starting with an 86 or 87 engine, but it should be noted that the SPS rod bolts installed by the factory are actually better than the ARP's. Many guys have been well into the 10's with the stock bolts.
Rods and rod bolts arent Buick V6 weaknesses. Crank flex and main cap walk are.
If the engine was never rebuilt and still has the original bolts, I would just resize the rods and add a girdle.
The girdle kit comes with extra long main studs. Keep your stock caps with the girdle.