Naaaa.. stupid is as stupid does Mr. Jim. and you're just getting the facts together to do it right. I'd say yer a smart fella. You won't have to modify the block Mopar buddy.
My first 68' 340 would twist to 6,800 easy. It was pretty plain, crane 267/292-467/494 max velocity cam, J heads and factory steel crank w/ fact rods. Some of my buddies, and others with brand X makes would say, man that 340 screams.
I'm building this one just to have fun with on a very tight budget.
I think thats why I want to keep that stock 3.31 in stroke to twist and hear and feel the unmistakeable 340 sound and power. But then the 4 in stroker makes BIG TQ w/ less effort and looks most are going that way.. but then..decisions decisions.
Best of luck to you on you'rs !
As we remember this Memorial day those that gave the ultimate sacrifice so we as Americans can enjoy our freedoms.