Need someone with custom PC experience to advise me.

So basically I'm trying desperately to get rid of the space between the mobo and the top radiator/fans as much as possible. My first instinct is to move the top radiator with the water cooling to the side and stick a thicker radiator on the top. But I can't find (don't know what to search) to find the right radiator thickness.

https://imgur.com/a/nyutK8N

Any words of advice?