Rebuilding a 74 Duster - Kinda...

340 with aluminum heads and intake , painted Chrysler Engine Blue ( including heads and intake ! ) ; 10:1 compression ; deeper-capacity oil pan ; reproduction '69 340 air cleaner , painted "Air Cleaner Orange" .

Keisler 4 speed auto , backed by either an 8.75" diff or a narrowed 9.25" diff , 4.10 gearing .

I like the small block deal better , as it's easier to make the car handle well , with mostly off-the-shelf parts ( big block torsion bars , de-arched Super Stock springs , front & rear sway bars , Firm-Feel steering ) .
I'd go no larger than 15" wheels ; something like 15x8" .

The 360 is a great motor ; however , given that this is a "cost is no object" build , I'd put my coins towards a 340 .