Can I turn this cast iron grill into a usable firepot with possible tuyere?
Will this be mounted inside a larger 'table' made with firebricks, refractory, or something else or do you intend it to be 'free standing' as is?  If free standing it should be suitable for light use (demonstrations and such) but I would keep to hand crank blowers as an air source.  I knew a smith who used a cast iron frying pan as a demonstration forge (he cut a hole in the bottom for the tuyere) and what you have looks similar in thickness.

It certainly could be used as the basis for a blacksmithing forge and IMHO would be no less efficient than a brake drum.