Riq is spot on re the heaters.
5 pin DIN socket? I use these from my local electronics store
Note the dimensions.
You should be able to find the equivalent locally.
I've designed and have been shipping a range of PCB's inspired by some big name amps.
Here is one of of my own builds that clones a Wizard MC25.
Look me up here if you're interested in grabbing some for your own project.