[LMH]

I have an unused 390 "mirror" block bored for a 428 rotating assembly. The shop that did it had to constantly sonic check the bore as they machined it but it did turn out ok. I ended up not using it and went with a 351W instead.
I should point out that the business in CA where I bought the block went through about 7 blocks until they found one bore-able. It wasn't cheap and I wouldn't go that route if I to do it over again.
Larry