Below is a recent local for sale craigslist Ad.
You could end up being better off going with a "less expense; but quality piece". If you were to use an outdoor fireplace basin & "accent" it with an old(pitted), but worthy rib-bone piece of iron to accent the curvature of rim. To give the eye candy of "old school"(if surrounded by rock, etc.)
A difficult case not knowing the other hardscape features involved(your design aspects).
The one listed in the link is over 1k, so, to me;
$500 for a Basin(newer & quality)
$200/parts to make worthy(Aesthetics & Plumbing)
You've probably already saved $500.
I have a $175 fireplace that is not a lot less than your stated spec.. It's a big bowl that sits in a cradle. No,it's not solid. It has a center hole vent that could be taken care of while picking up the "accent" feature
It's not say that "with a little effort($$$)" you couldn't find a cheaper (damaged "period" piece). But; Time=$$$.
Why pay for the "Period" piece-unless it's the ultimate "want" of the Customer. For whatever reason.
Given, it looks the same when completed?
To me, it would all depend on how much of the kettle would "show" when completed as to the proper direction to take.
IMO, I have several concerns.
Obtaining a "Period syrup kettle" for reasonable $$$.
Obtaining the kettle in due-time.
If the entire outside ring needs to show & it's a critical "Want" of the Customer(Period piece); your screwed. Gotta get a "period" piece & they pay for it too. Otherwise, some "aged" metal fabrication CAN be done for this purpose.
***I CAN PUT YOU IN TOUCH WITH A VERY FAIR & REASONABLE LOCAL BLACKSMITH*** If need be.
He ships his work all over the country & has many references; personal as well as online.
Good luck & hope to see a "Finished" pic soon!
Had to use a few quotes to emphasise several points above.