The other side is definitely open. It doesn't even have a barrel on!

I wanted to leak test it at the earliest point possible so until I can get the left side of the engine to hold air, I'm not continuing.

Very confident the cases and seals aren't leaking. I had a lot of leaking around the insulators. Now they're threebonded, the next weakest point appears to be my exhaust plug.

Hopefully once that's sorted I will get the confirmation I've been waiting for.