Many older instruments don't use the EOI line, but also "Must" have the correct command terminator byte (if one is specified) no more, no less..
It'll all be documented in the individual instruments manual.? The fun bit these days is getting "modern" bus controllers to play nice with older non IEE488.2 devices.
Don't rely on the more modern high level function calls, start with the low level byte by byte stuff, and run a bus traffic capture too, guessing Agilent has an equivalent to NI's 'I/O Trace' (was NI Spy) program.