I sure like what BG has brought to the table in their Six Shooter
set up and from what I've read, It does have advantages over the
original Tri-Power. I would not be the least bit afraid to run with one for power per $$, as well as for conversation. Obviously my 'bird isn't stock, but I personally like the 'authenticity' the T-P brings to it. Besides, I got that manifold and carbs back in '76 when it was just an old used part a guy had on his racer. 50 coconuts as compared to todays costs of at least 1500.
If I change from my Tri-Power however, it just might be for fuel injection, and almost certainly on a complete different engine.
As far as the BG setup fitting under the hood, I would bet there is plenty of room.