regex - .NET Regex Balancing Groups and syntax matching

Question

I have some code containg null == myvar and want to change it myvar == null. Variants of code

if(null == myvar) > if(myvar == null)

if(null != myvar) > if(myvar != null)

if(null == myvar && someother) > if(myvar == null && someother)

if(null == foo.SomeFoo(bar).FirstOrDefault()) > if(foo.SomeFoo(bar).FirstOrDefault() == null)

I have solved the 3 first cases using this regex

null ([!=]{2}) (.*?)([ \)])

And replace with

$2 $1 null$3

Though for the last case it will replace with

if(foo.SomeFoo(bar)==null.FirstOrDefault())

The problem is it looks for a space or a parenthesis, but in the case of parenthesis it needs to balance them with opening parenthesis

I need to use Balancing Groups somehow but I do not understand how :D