I have a Great Planes Sweet Thing P51 Mustang with a Super Tigre .75 in it and the .75 is the same physical size as the ST.90.
One thing my P51 does not lack is power, and pleanty of it

, I only wish I put the .90 in it.
Make room in far back to mount the battery as my P51 uses an oversize battery for ballast as far back as I can get it
Have lots of fun!