As for the alternator sticking out into the passenger seat back area, that can be fixed two ways. The first is to cut 1.00" from the long mounting boss under the alt, and use that cut piece as a spacer between the alt and the outer part of the mbig mounting bracket. This moves the alt back with a stock length mounting bolt, and utilizes the middle pulley groove on a stock crankshaft pulley. The useless idler pulley is deleted and a shorter vee belt is needed. No other changes are required.
The second method uses the upper mounting intended for an air pump on wide-body '80s GT-5 and GT-5s engines, and also requires using the middle sheave on a stock crank pulley. These later brackets were obviously different from the earlier brackets but bolt on perfectly.