I don't know how you can "just virtualize those iscsi drives", at least converter can't do that. Perhaps this article might help: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1005241
The "converter way" would be to do a P2V with synchronization; the downtime will be a few minutes.
HTH
Plamen