I really don't think you are going to have any issues at all with customs.
Either way.
Carry on xrays are not a problem.
Bring your own or buy here no problem
Take it back or pay to develop here, no problem.
Customs are not going to be interested in film camera gear, but it is a good idea if you can to register the major pieces. Here we get the RCMP to fill out a little card with serial numbers to carry with us. But I have never been asked for it in 40 years and I carry serious gear.