My honest opinion on it is B1 heads on a stock Mopar block isn’t going to last long. I raced with Tom Hemphill for many many years and he probably built more B1 headed engines than most will ever see. Stock blocks are a throw away item at that horsepower level. It’s not will it break, it’s when will it break. I ordered and bought my Keith Black block back around 2007 or so when it only took 6-8 months to get a custom block made. Then I feel into a very nice Mega block that I almost waited to long on. At that time I had a third duster and planned on having it sitting here ready to go if my son or I needed it. He moved so I really didn’t need the car so I sold the block with a brand new 505 assembly. That was a nice 8 second package.