Looks good. Taking a Magnum back in time to V-belts. Easiest to mount the compressor solid and use the alternator as tensioner, as you do. Looks like 1-slot w.p. pulley shared with power steering pump.
I may add a Holley TBI eventually. I have their Commander 950 TBI on my 1965 Newport 383 and 2 extra ECU's and harnesses, but no extra Commander TB though have an older Holley Projection TB which can work (other than no IAC). Eventually, I'd like to install a Magnum beer-keg intake to get MPFI. I have one but will take CNC work to get studs to fit my 1965 heads (16 deg off vertical bolt angle). You could bolt a Magnum intake up directly, but the Sniper ECU is built inside their TB, so no way to leverage it.