My 340/420 Stroker Build

Dang, man! You're fearless with that numbers matching block....lol. I have a 70 A66 Challenger that I have owned since 1979, and it is all numbers matching. 99% of the parts are even date code correct, so when I get to it, it will be a boring stock type resto. Looking forward to seeing how yours goes and some pics. For what @Mean416 was saying about refacing the lifters, check out Powell Machines videos on You Tube. He's in Iva, SC and seems to really know his stuff on that subject.

At 500 hp or less with street suspension setup and quality components/machining, is there really that much chance of hurting a block than ~325hp 340 setup?

Limited traction, street stall converter, street gears...