Patek Phillipe

hi,

I have been offered a 18k Patek and would like to know more about the watch before I purchase it.

There are two sets of no's in the case back and are
2603473 and 2482. then there is another no on the engine 707523.

What I need to know is which year is this and how much is its rough value?

The three hands are not original and so is the leather stap and buckle. No box or papers. Looks like the six marker on the dial also has been replaced by a non Patek bar. Can send picture if necessary.

Thank you for your advice.
Rgds
Budds