GC Firewall Heater Bulkhead/Heater Tap

[karl_2ltgc]

Hello Comrades,
Im looking for a solution for a bulkhead fitting to replace the standard rubber setup on a GC galant. Custom setup is fine, can weld bits back in etc.
Any ideas on bulkhead fittings, I've looked at summit and seems -10AN is popular.
Further, can you buy new heater cores? If so Where?
Lastly, any recomendations for a replacement heater tap?

Pics here - https://ibb.co/album/YXc066

[Fingers]

Last time I needed a heater core the local Natrad dealer sourced it for me.