I would suggest always check MSA drive matrix for support perspective before using any drive in MSA box,
https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04315770
As per above I see
for spare part 601777-001 -> product ID: AP860A and this is 600GB 15K 6 Gb/s SAS LFF Hot-Plug
for spare part 787656-001 -> product ID: J9V70A and this is 600GB 12G SAS 15K 3.5 in LFF ENT HDD
Only difference is backend speed. This only matters depends upon what backend speed Chassis you are using the drive. So in this case you shouldn't have any issue.