Try this and remember, on the small block chevy, the knurl before the thread sticks up past the starter housing about 1/8 inch and rests in the block. Without the knurl inside the block, you will have starter and ring gear failure. This is from past experience where my block was cracked from wrong starter bolts. Try this link
http://www.dormanproducts.com/c-674-...ing-bolts.aspx