I *had* and 030 at 60Mhz, and that was on a blizzard without a scsi kit, never tried the scsi kit but I got the impression it'd be flakey at that speed trying one. The 030 its self never seemed hot, neither did anything else on the board but I knew it was pushing it.
Sold it on ebay, some lucky sod has that card now and I'm left looking for a big box.