Reusing a new construction window

[qoncept]

We've been busy for the last year repairing our house from a flood and the project has kind of ballooned in to doing just about everything we can think of. Insulation was so cheap that when I was buying for the basement, I bought enough to do our garage, too. The existing windows (3) in the garage are just a single pane between studs and slide through a slot in the "header" to open.

I've got 3 new windows to replace those, but I also have a 6x4' window that we took out of the house and replaced with a sliding door. It's a new construction (flange) type vinyl window, but the flanges are all cracked and falling off. This one will be a new window, not replacing an existing one in the garage. My plan is to just run screws from the inside the frame in to the studs, since I'm not too concerned with a garage window being beautiful.

But... I thought I'd run it by some people that know better than me first. It's a very nice LoE window with beveled glass that matches the house windows, so it'd be a shame to throw it out (and I could definitely use some more air circulation on that side of the garage). Any thoughts?

For anyone interested, "insulating the basement" turned in to tile, drywall, a new bathroom, new basement windows, insulating and interior wall-ing the garage, rerunning romex to accomodate it, new garage windows and doors, new shelving and workbench, and ... paving our driveway. Gonna be rough with winter coming and football season eating up weekends.

[pushkins]

Is there nothing left at all of the nailing fin on the window, it is a much better idea to try to use the remaining nailing fin that to basically destroy the window with internal screws ?