
Hey JHanna,
> Everything works fine when running the BFG9060 at 50MHz.
I don't have a 4000T, but ran my BFG in a 4000D with PIV, DENEB, Ariadne, and (more relevant to your scenario) an A4091.
I also encountered SCSI errors that were more reproducible with the BFG at 100MHz. I measured +5v at one of the Zorro cards with a multimeter, noted that it was low, and bounced around when wiggling the Molex connector at the motherboard.

So I could hold the connector in a direction that provided better contact, and the problem would disappear.
I don't know if this issue is as common with the 4000T, but might be worth a look if you haven't already ruled it out.