importing firewire 400 devices

I previously used Tiger O/S with FCE and FCP. When my HD died and I purchased a new 27" iMAC along with FCP-X. I shoot on a Canon GL-2 (mini DV tape) and it has FireWire 400 ports. What is the best way to get my tapes into FCP-X for editing. This new iMAC does not have any FireWire ports, only ThunderBolt and USB 3.0.

I've "built" a solution, but it's causing sync-ing problems. I have a ThunderBolt adaptor to a FW800 to a FW400, which then connects to my camera. Too much lag creates my audio and video to be out of sync.

How can I get the cleanest footage into FCP-X. Remember, my new iMAC only has Thunderbolt and USB ports, no FW ports.

cheers,

Jack