Bose 301 modifications

If they still make sound, I wouldn't do any mods to them. Your daughter wouldn't notice the difference anyway, and I bet she will be thrilled to have them as is. IMO, your free time could be spent more productively.
Just my 2c...

Tom

Leave them as is. The 301 was one of their better speakers.  The HF rolls off due to the use of the 3” tweeters, but overall their sound is warm and unoffensive.  

If you want to have a fun little project, build whatever inexprnsive speaker kit you like either from madisound or parts express.  There’s a cool little portable, self amplified bluetooth boombox for $250 that uses a 6” bass driver, 2 3” mids, 2 1” silk tweeters.  

She can help you paint it!

Do you have a receiver in mind to use with the bose?  Source?

Fix the foams and if you must tinker, add a film bypass cap and low ESR electrolytic to replace the factory cap. Better yet, get your diy kicks by building your daughter a kit from parts express. The Samba MT will set her up for a lifetime of listening enjoyment for under $200.00.

Best thing to do with 301’s without changing out drivers is to power them with a receiver with a loudness function (turned on) and a bit of bass and treble boost....they’re at least listenable . This is for 301-II’s
I took mine apart because they sound like there’s little to no damping material inside the cabinet, but there is lots of it, box seems simply too small for that woofer.

The Woofer is run wide open too, seems very little thought was put into that crossover, just something simple and generic to keep the low frequencies out of the tweeter.