I'm looking to change the side window in my bus, its an 1987 Holdsworth Villa 3 high top. At the moment it has a louvel window behind the kitchen

I want to change it to a fixed window because some little sod forced one of the pannels to brake into the van. I brought a standard window for the bus but it doesn't seem to fit, its approx 2-3 cm too wide. Has anyone else tried to replace a window in a Holdsworth Villa and had this problem?
When I removed the louvel window the hole in the pannel measures 108cm X 40cm exactly

Does anyone know if Holdsworths have smaller windows or where I can buy a window that will fit.
Any help greatly appriciated,
Cheers,