Many Siamese Mausers are missing the Floor Plate. Here is a way to remedy the situation.
Conversion for Siamese Mauser floor plate from Japanese Model 38 floor plate
Showing Cuts made to to adapt rear of follower, about 1/16 deep.
On either side of the half Moon area. Leave the area n the
center of the Half Moon for the trigger release.
Cut away material to leave a tab on the rear to lock to trigger
guard, Go slow at the end so as to not remove too much material.
Cut under front of locking plate, on front making a deeper to recess in trigger guard.
Takes about an hour, to cut properly. With checking
fitting. A follower form the same rifle can also be fitted.
We did one of these, and it worked great.
Good Luck