What is the best way to purchase a vehicle with finance interest?

I ran the PPS search and it spat out the name of seller and their address who the security is registered against (2 persons).

Myself not being familiar with how the security interest works here in NZ, I believe I could do it 2 ways.

1. I pay seller agreed price in physical meet up. Take vehicle immediately. Await confirmation from seller of settlement (what proof can I request?). Officially transfer ownership (This places a great deal of trust on seller to settle, and risk to myself of taking vehicle prior to changing ownership, acknowledging the fact that I have the persons names and address) 

2. Request settlement certificate from owner/finance institution. I pay finance institution directly, and pay the seller the balance, both in physical meet up. Officially transfer ownership and take vehicle immediately. 

While option 2 sounds the better way, the seller is pushing back on that option. I also do not know the settlement balance.

Are there any other ways to do this?