Someone traced out the connections for the SE/30 SCSI chipped and posted them. You'll have to hunt for it though. You might also check the Wiki. It might be in there. But there was another SE/30 thread within the last few years about replacing the SCSI chip and then discovering that it was a corroded connection or trace.

Thought of a few search terms that would help. Here's the thread:

http://68kmla.org/forums/viewtopic.php?f=7&t=12985&hilit=SE%2F30+datasheet+53c80

Zuiko21 says he has a schematic showing the 53C80 connections somewhere around mid-thread, so you might try asking him about it.