It won't work connecting up a widescreen bordmonitor to a navicomp which is setup & running a mono-screen display.

There are divived opinions on recoding a Mk4 that came from a mono system to work with a 16:9 - seems it can be done.

Your best bet is to get hold of a Mk4 DVD navicomp and substitute that and the mono unit - and you will need the gubbins to move the air con panel to give room for the larger display....

Someone who has done a similar retrofit may come along to give you some more in-depth advice.