Mast Step Bolts - Replacement Recommendations

[allanbranch]

I have a keel stepped mast which is down for repairs. When the yard pulled the mast the step was stuck to the mast base and the step's bolts broke off. The keel is lead (morgan 30). The step got lost in the yard (I'm a moron). I'm rebuilding one with fiberglass.

Should I use aluminum bolts or stainless?
How long should the bolts be?

[allanbranch]

I ended up drilling 1" holes into the lead keel with the intention of filling the hole with epoxy.Then I took SS carriage bolts into the hole with a washer in the hole. I cut a plastic barrel to make a separation between the lead keel, the aluminum step, SS bolts and mast.

See attached pictures.