Please post the progress.
I, for one, will be watching. I have the same idea. Dual use, but it comes with some difficulty. The basket, with its base, can be somewhat heavy empty. Add char and wood, the weight increases...
Maybe simple is best...I have three alternatives, neither is neat.
One is to drill four holes at point near top where the basket will be close enough (crosswise), to grille with grate near top to hold coals near cook surface grate, maybe using orig Weber coal grate...the holes must be large enough to run either steel rod or some rebar through to support basket...and can be removed and the holes sealed with bolts and washers. Uneven bars can use U-clamps to even somewhat.
Or, craft long-legged rebar support platform of sorts to place in bbl, same results...but no holes in bbl. Just drop it in place...but more yard clutter.
Or use straps curled about edge to support platform and coal basket, if top will allow it.
Cranks and so on in side well-used bbl seems to be begging to constant care...
All in all, good idea to have alternative that is Weber-like, particularly if some in household prefer grilled over smoked, which is what I have encountered.
It is just after a time, smoked gets to be too much for some and I can understand that, as much as I like it...and meat is getting very spendy, isn't it?