Id be speaking to the finance company (in conjunction with the present keeper). He most likely needs the $ to pay out the contract.
Get a current pay out statement.
Figure out what the balance is for the owner.
Pay out the contract, pay out the owner and arrange for transfers at the same time/venue (financiers offices?)
Get receipt copies from finance co and receipt from owner to complete transfer of rego.
If you were trading a vehicle under finance to a dealer, they would do something similar. They would just write you out a cheque for the balance, less outstanding contract. They would then pay out contract and transfer rego.
cheers, mace.