Galvanised Sill query

Hi Guys, I am new to this forum but hopefully you can help me.
I am going to rebuild my Land Rover 110 on a galvanised Chassis and Bulkhead. After spending loads of time tweaking it for MOT the bulkhead had a big hole in it and given the work to replace I decided to go mad and do the chassis too.
My question, I have galvanised sills from YRM. If I need to replace the B and C posts how can I attach these without breaking the galvanising on the sill?

They need to be welded on imho.
Not enough metal between the two to bolt them on AND they are the seatbelt mountings too.

So buying galvo sills was a waste of money as I need the grind the galv off to weld.
Dont tell you that do they!?!

Hello and welcome

Hi brianp38dse

Welcome to the forum