I'm late to the party, but I've done exactly what you are wanting to do and it cost me $25 and I've shot multiple packs with the system so I know it works. Only one potential snag, however.

I sourced a "Graflex Pack Film Adapter" which was $6 on eBay. With a rotary tool (Dremel, in my case), I cut off all of the pack film bits, including the latching back door. The only bits left were the dark slide and the surrounding frame that interfaced with the GRAFLEX style back on my Speed Graphic. Not a spring back, not a Graflock. Next, I took the CB-103 (AKA Type 100 back, AKA pack film back as you call it) and with the normal 6 screws, attached it to that Pack Film Adapter's framework just like they get attached to the Forschers/Mamiya style attachment.

I needed to do this to get something to work with the Graflex RB style back as the PA-145 and 405s are made for Graflocks and won't work, plus I'm cheap and refuse to spend that much money on something I can do myself with a little time. I know they made "Graflex Pack Film Adapters" with the right interlock for a Graflock style back, but I'm not sure what the model number is, nor if they are exactly the same, so there is your (potential) snag.

I haven't needed to get super precise with the focus depth (I know it is off a bit but it is easily compensated for), but you might find it bothersome and need to do some fine tuning.

See attached image for the final product. It's not fancy but I don't need it to be, but you could make it look as professional as you like. Would be happy to help if possible, let us know if you get something to work!!!