Since I know she'll ask, how much would this gun be worth and how much does the alteration affect that?
I wished I could give you a good figure but there are few First Models being sold to get pricing from. Also, condition is very important (and hard to decipher from the pics). As for the shortened barrel, it will lower value but how much depends on the quality of the job and how bad a collector wants it.
That said, here's a 2006 price listing (values have increased since) from the SCSW:
Fair - $250.
Good - $375.
VG - $500.
Exc - $700
Exc+ - $1200