Newbie question studs or bolts on exhaust manifold

[Mr meteor]

I am assembling an 8BA and I recently acquired some used exhaust manifolds and a crossover pipe.

I am shopping for the correct fasteners to attach these to the block. I’m finding a lot of bolts but not a lot of options for studs.

The header bolts I keep finding are marketed for the 8BA but seem to be 1 inch and I believe the holes in the block are 1 1/8.

Does anyone know where to source studs? Or is it ok to use these bolts?