SAIS tube block plate for Hewitt kit, broken stud

Yes, trying to install the metal block plate, broke off the nut on the stud. Only one, but I fear they will all break. Soaked in penetrant for 2 days, even used heat. Don't want to try the others for fear they break too.

My options are limited, drill out? (no way)
Remove heads?
try to block the tubes from where the air injector is?
Go through the firewall?

Anyone have this happen?
Thanks in advance

 

Option 3, don't worry about the block off plates. Not ideal, but if the pump is bypassed then I see it as fairly low risk

Option 4, new headers and full custom race exhaust!

 

I broke 3 out of 4. Left the one side alone and safety wired the other snug. May get in there one day and make it better.

 

I installed the Hewitt kit on the actual air pumps themselves. Same shape and size as the SAIS tube on the manifold.

https://www.tundras.com/threads/how-to-00-04-headers-onto-05-06-motor.97796/page-2