[gijoe77]

Welcome and congrats on the Indigo2 acquisition! Keep us posted on the condition and specs when it arrives.

I don't think having a CDROM will be a requirement to install IRIX, you might be able to do it over the network, see https://forums.irix.cc/thread-451.html.

For my indigo2 I stuck this drive https://www.ebay.com/itm/HP-412751-016-3...2877971743 into it with the assistance of a 50pin to 80pin SCA adapter https://www.ebay.com/itm/SCSI-SCA-80-PIN...2227557176

your looking at 10MB/sec max SCSI speeds, but I tested out the SD2SCSI speeds and it wasn't really usable for IRIX 6.5. SD2SCSI was perfectly doable for IRIX 5.3, but you would really have to have a specific need to run IRIX 5.3, specifically to run some sort of software that didn't work in IRIX 6.5