Brainstorming an Idea, whats your 2 cents

Sorry to hear your problems with the rebuild on that engine. I can understrand your frustration and desire to fix the basic problem of a crappy rebuild and low oil pressure. But I dont think it will be a basic swap changing to a 4.00" crank and milling the pistons.(providing KB says it can be done), Id research it more before spending more money, could end up being a very expensive engine and still not correct.
Muscle Motors recommended a Milodon 7 quart pan/pick up, and high volume oil pump for my 450 hp 408 build. The stroker route will require better heads and bigger carb to be effective, 1 & 5/8" headers were a bottle neck on mine, "had" to spend more $ for 1 3/4 " Hookers (big improvement). The stroker thing is cool, but my 350 hp 360 in my other Duster is cheaper to build / cheaper to operate and is great for the street .