I also have a 440 from a motor home which was stroked to 500 with 550 hp, 323 limited slip from 1975 Imperial and 727 column shift on my 1972 Fury III. I ordered the lower Edelbrock manifold and it clears the hood just barely with dual snorkel. I am working on getting the shift to work around my headers 2.5" TTI (did you deal with that yet?). Also working on issue with adjusting kick down on 727.
I have a firm feel suspension and cop car wheels - I am sure it would be considered a sleeper as does yours since most people would not expect the beast that lies within.
I am getting a local Mopar shop to help me with my mechanical issues. I need the paint color sanded, waiting on SMS headliner and seat cushions, then I will post my sleeper photos and videos.
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Good luck - on your project. Post burnout video someday as will I.