There are actually 3 model 25's...
The Model 25 Slide-action (pump) repeater, 1909-1910, rare as hen's teeth, worth around $400 in 90%+ condition...
The Model 25 (also 20/80/780) with the curved box-style magazine...1940-1965
and the Model 25N which has the Modern Stick-mag...1984-1988 followed by the 880/925/980/xt22
The first two can't be modded much...and pretty much shouldn't be...the 20/25/80/780 can trade stocks & some components, that's about it...
the 25N shares parts & stocks with the modern 880/925/980/XT22, so you can go wild on those with modern gear!!
Difference between the 25n/880/925/980/XT22?? The stocks & triggers were upgraded as time went by...that's it.
All of 'em tend to shoot tiny little groups, so any way you go, it'll be worth it!!
For $100, either bolt action will be well worth it!! But try to haggle 'em down to $80 anyway