If it fits in and the top looks right height, Does the slide work as it should when you hold it in?
You can easily cut a notch in the right spot, i made a Ruger 40cal fit my 941
Do you have a proper mag now? if so , measure down from the top to top of notch, that will be where the notch should be.
I got a CZ75 mag and had to take one stroke with a file to get it to lock in on my Jericho, works good . Tradex has a good price.