I had my '99 360 block sonic checked before it was bored.... and they pretty much told me that with boost - 4.030 was really pushing it. All I know about them is what my machinist told me (for what it's worth) ... He thinks if anybody wants to go 4.220 on a Magnum block - they will have to install 8 sleeves.

Once again - I am NOT an expert - just a consumer that's passing along info second-hand.