I also had an Extra Special. Got a Fun 51 in the box in my shop.
The only difference is the fuse outline.

I had a ST45 on mine to begin with but it was kinda sick. Poor results.

Put an OS 46fx in its place and it was a hoot.

I think the 40 will fly it but go ahead and get you a 46 TT, FX or Irvine.

It'll be a blast.

________
DoubleD