replacement seat track mounting bolts

Today we assembled a pair of brand new re-popped seat tracks for 1970 A-body high back bucket seats. My associate and I are going for a full restoration on this 4 speed 340 car that had been in the hands of Frankenstein himself. We were missing the 4X hardware also for seat tracks to seat frame. Unable to find a 5/16-18 bolt with a reduced size head grade 8 or better , so we settled for header bolts which function perfectly and I have a TON of them saved from the last 4 decades ! Just don't tell nobody ...

20200104_160050_resized[1].jpg

20200104_160101_resized[1].jpg