Changing Tripod Mount / Foot on a Hasselblad

I recently purchased a Hasselblad 503cx camera body, but realized after buying that the tripod mount on the "foot" doesn't fit my other Hasselblad accessories. I have a couple flash grips and an Arca plate for Hasselblads, but all of them use a 3/8" thread --> the foot on my 503cx has a 1/4" thread (like this). Can the foot or mount be changed easily? I removed the plate on the foot to take a look and it appears that there is a tapped circular tripod mounting "disk" mounted under the foot itself - can this disk simply be changed for one with a larger hole? If so, where can I get one?

Thanks in advance.