With all due respect, while Model 100 magazines will fit & work OK in a Model 88, they will keep the bolt/lever of a M-88 from closing after the last shot - which can be a +/-, depending upon the shooter's mindset.
Just to say it, those Model 88's and 100's were about the prettiest rifles of their respective types that I ever saw. Dad had an 88 in 308 and my cousin had a 100 in 308.