Your tanks not terminal and I do have tanks. But:
To have a nice tank you will have to re-chrome anyways, so strip the whole thing before welding. I would think the low cost method would be to remove chrome around the cracking and have it professionally welded (if you're no better welder them I am). You could paint the complete tank which there are nice examples on Richard's rebuild site area.
I took a real sow's ear tank and made a silk purse out of it by stripping, splitting the tank halves (grind off no more metal than necessary), de-denting for the inside, wire brushing inside surface thoroughly, added 1/8 npt cross over ports, rewelded, and leak checked. A beautiful chorme tank is waiting for paint.
With the success of this process I plan to do more tanks.
By the way Ziggy, I believe to chrome over solder you must have a copper layer between it and the chrome. Not all chrome shops use copper.