Bruce,
That's a lot of mods packed into a small footprint. Very interesting.
Could you post a photo or two (if you took any) of the boiler before and after removing the flue?
Great job and up to the SPS standard of high quality + inventiveness.
Scott
Hi Scott ,& thank you for the compliments ( as well as all the others)
I did & usually do take build picture's even though I may not show them, I did take just a few of both ends of the boiler....unfortunately no "before" shots , here are two...
top of boiler , with dome for the chimney ,this would make an excellent spot for a S/V or a water fill plug in my next build.

And the bottom of the boiler , this is another thing I would do differently on the next build, I never planned on removing the flue when I put the cartridge heater in, the next one will have the cartridge heater in the center of the Brass plug with the drain pipe offset slightly , the 1/4 circle piece next to the brass sleeve is for a tang & #2 bolt to hold the cartridge heater in place since its a vertical application in this instance.

I do have a brand new D455 & will be modifying it over the next week or two, if enough interest I can post a build thread.