When was the c4 built? It must be over 30 years of age if LHD. Otherwise under30 years of age, it must be RHD. Being on club rego doesn’t automatically allow full rego in NSW.
There are cars registered in Victoria that will never be allowed to be registered in NSW.
If unsure that you are able to get rego in NSW, get the full details off the car you are interested in (VIN, engine number together with the current rego details). Then contact the Vehicle Technical Unit of RMS at Parramatta and they will advise you what you will need to do.
I recently purchased a c3 in QLD on full rego and drove it back to NSW. To put it on club rego, I only needed Blue slip, rego details from QLD and some paperwork from NSW corvettes. The rest was easy. Good luck, the guys at RMS are your best guide and will give you the right advice.