Normally SCSI I equipment uses a 50pin centronics-style connector (the type with the wire clips) or a 25pin D connector (this is what the A3000's built-in has).
SCSI II usually uses a high denisty 50pin connector (I'm not certain which type the WarpEngine external SCSI is, IIRC you needed an extra cable with an external connetor on it) so you will probably need a new cable with a HD 50 connector to connect from the Warp Engine's external connector to your external exclosure otherwise it should work fine.
There's some more information on Warp Engine SCSI configuration at the
Big Book of Amiga Hardware.
HTH
Robert
