Need to re-tap cutlass housing bolt

[gfuller]

Fellow Albin owners - It's been a while and a very cold winter, but yesterday's heatwave bringing a whopping 45 degrees got me back into the spirit of summer.

I've been putting this one off since last fall. I need to retap one of the 3/8-16 (bottom) holes that attach the cutlass housing to the keel. A couple of general questions with this:

What size should I go up to? 7/16? should I drill and retap or use a Helicoil rig? I'm not sure how much meat is on the backing and I'm pretty sure there is no solid way to know visually.

Also, is silicon bronze the only bolt metal that can be used here? For the 7/16 x 2-1/2" I'm having some hard times locating them, next would be 1/2" and those are pretty available.

Would stainless work?

Thanks all!

[gfuller]

Drilled and tapped to 7/16 14 NC and worked perfectly. I will say those backing nuts or whatever they are are quite thick and won't go anywhere.