Honda part number for the bolts is 90128-382-670
I bought four at https://www.partzilla.com/

I don't know if they are needed but some have had problems with them breaking so I figured I would replace them when I had the sprocket off.

JT Rear Sprocket JTR279.30T 30 Tooth 1 22.99 22.99 248591
USPS Priority 2-5 Days 1 0.00 0.00
Total $22.99

From
http://www.oldbikebarn.com/Motorcycle_Parts?search=JTR279