[morzh]

There were two problems: 1) height of the output transformer and 2) height of the 12uF/10uF electrolytic cap.

The height of the transformer I was able to reduce by removing the rivet I used on the speaker's right side, as it held the extension that then the transformer was riveted to. The head of the rivet added that 1.5mm I was sorely in need for.
Now the transformer is riveted by just one rivet and another ear is bent around the speaker's transformer holding plate - does not let it pivot. At some point I will epoxy it, but it holds the way it is.

Once I fixed the transformer problem (it still touching the top but not really propping it up) and tried to slide the chassis in the cabinet, I realized that I was having another nasty - the electrolytic cap. First I couldn't get it, why - it was its own cap. Then I recalled that instead of sawing off the bottom I opened it as I would a can, and then stuffed an potted it. The opened flange added the height.

I desoldered the cap, took it out, took the hacksaw blade, round-cut the flange, reducing it by about 3mm, then nipped off the excess of the potted plastic, smoothed it with a heatgun and put it back into the chassis.

Now all fits! Squeaking by, but fits.

Here it is.

   
The speaker's cone patched and the speaker installed.
   
Same.
   
Transformer view.
   
Assembled
   
Same.