Has collected for new project TVR1A - I think to build Russian torpedo boat LUGA. I calculate the minimal sizes of the boiler. The width of the case 13Sm height 9Sm. is long 1m 29Sm. an operating time 15min. while I think about  http://www.maccsteam.com/Horizontal_Marine_boilers/Small_boiler/small_boiler.html

Hello Oleg, I have a Graham TVR1 engine too and was thinking of painting the aluminum parts black, just as you did. What paint did you use?
And did you cut out the cylinder base plate? Because the one I have is rectangular in shape. Yours looks much better.
A very nice engine!

Sorry I can't help with boiler size.