If an L series fits straight in then all Nissan engines do also :))))

The only way it will fit well without crossmber mods is to use the L16/18 block
which is 20,mm shorter than the L20, then have a very good sump made that clear
the crank enough not to cause issues and fit a shorter Z series head from a z18/20/22
as they are much shorter than the L series heads.
Then you will have to use a Z bellhousing to slant the motor biased to the passenger
side by at least 15 degrees. Custom inlet and exhaust manifold etc.
All of the above should see it fit must use the Z series head which is 10cm tall spot
on with rocker breather out the side or back. Ive measured them recently.
Someone else can tell you how tall the L head is with rocker cover.