As for header clearance, I had a Duster with an RB runnuig Indy EZ heads, and TTI headers.
Pitman and idler arms did hit the headers @ full lock.
Rt side spark plugs were something of a chore, especially #6.
I didn't do the engine swap, but seems to me a low-deck would be a more friendly fit.
Photos are after I cleaned things up, in case a reference is needed.
LOL, I had a 451 low deck with the old Bagshaw headers in my 73 duster....for #6 I drilled a hole directly across from the plug in the fenderwell and used a Plastic Electical Conduit push-in plug to seal it back up. Made changing the plugs a Breeze. here's an old Polaroid from like 30+ years ago, lol
As far as A body's I know the Early Pre 67's need a dropped centerlink, so I would imagine the later A's would need one too but I honestly think it was straight and the Milodon 7 qt front sump fit great.
