85 300TD mismatched keyset

[Carrameow]

I bought her from an unknown owner who had left it in a field. what sealed my mind was the AOPA sticker-"aircraft private owners association"--i guess an airplane owner would have maintined the engine well.
One key works the ignition; another works one door; the ignition key works the other door. i would like to standardize the lockset to the ignition key. I will spend a lot to restore this car, but hopefully i wont have to spend a ton on the lockset. Any ideas for a one-key lockset?
I realise the original proper key is tied to VIN and you need a title or registration to order it.

[can-do]

Greetings,

As with most MB vehicles, there is a master key that operates everything and one that just gets you in the door and starts the engine, doesn't work on the trunk or glove compartment. Please review what you can and can not do with each key first. It is possible that a door was replaced with another hence another key because of the different lock. Please explore a little deeper and post a reply.

Charles