Sun-labeled ones are what you should watch for.
They all seem to have the 800bpi option, and are SE SCSI.
--
Spotted one over at Weird Stuff for $50 today.
Sun PN 596-1219
The 800bpi option (replacement R/W board) PCB
part number is 07980-66531
http://sunsolve.sun.com/handbook_pub/Systems/Sun4/RMVBL_OPT_680.html
for a parts breakdown