Just catching up on this, in case it helps i also had to rejig my pedal plate and steering column mounts as well! So (as ever) i went a bit OTT i did a frame extension in 25x25x3mm steel box section with a 4mm steel plate on the top.
After that my bulkhead was fabricated in bonded and rivited aluminium which i got from metals4you.co.uk
I started with this
But also ended up totally altering the steering column part so that i could fit space behind my flush mounted instruments and ended with this.
Hope this helps a bit?