Oh, just to add......
There are new combo cpu/driver boards available for these games that eliminate a lot of the 30 year old problems these games have.
If the backglass and playfield are indeed in good condition, it might be well worth your while if you can get it all happening for a few hundred on top of the initial purchase price.
+1
The backglass is the key here, and the other thing to check is if this game has electronic sounds or chimes. If it was a machine that was manufactured with chimes - then check if they are there.
If you are happy with the playfield, backglass and cabinet, you will need the Combo board, a power supply board and you didn't mention if the game had displays ?
So here is what you are looking at ;
Combo board -
http://www.rottendog.us/mpu327.htmDisplays -
http://www.rottendog.us/DIS326.htmPower Supply -
http://www.rottendog.us/WPS346.htmYou may need to replace the connector and pins - depending on the condition.
I'd say a World Cup would fetch $1200 - $1600 in reconditioned working order.