Small block headers: worst to best fitting. List your experience.

If anything I'm aligned a little more toward the passenger side. I bought the Borgeson box last year so it's gotta be the newer version. This is also a magnum block, if that makes any difference.
See the chart in post 58. Your whole engine should be 1.25" closer to the passenger side of the car as well. Verify all of these measurements to eliminate misplacement as a potential reason for your clearancing woes.