Thanks for the pics Mariusz. 
Is the conversion plug n play or a lot of reworking?
Special Christmas announcement? 
In my case - easy.
Remove voltage regulator and install it on oversize heatsink.
Drill the opening for extra long 6h30 tube. Install tube pot and heatsink raisers.
I also had to replace the input selector switch (my fault).
Your kit might be totally different then what we have.