Need some light with this '79 Marshall MKII Super Bass

Hi everyone!

I just bought a '79 Marshall MKII Super Bass head. It works and sounds great but his last owner have no idea about the amp. Only that has been possibly modified to SL and have a master volume control plus an effects loop (desactivated) and two inputs on the back panel conected somehow to the power tubes.

The "elements" on the board suggest that has been modified if I compare it with my '78 2203, but I have no idea about electronics. I would like anyway to bring it back to the Super Bass specs, so any help to know about the amp will be highly appreciated.

Thanks in advance!

It's had a lot done, but I can't really tell what by the pics. Output transformer has been changed. It can be converted back.
Jerry

-ive never even seen that color of board before

Almost everything single component on that board has been replaced.

That might be a whole new board in there.