I changed the keel bolts on my Ranger 26 one at a time. After the nut was removed I double nutted the stud and removed and replaced the stud. Those that still didn't want to turn came out using a pipe wrench on the stud.
I bought stainless steel all tread and cut it to length for replacing the studs. I also used a lot of penetrating oil.
I then sandblasted the keel and faired the rust gouges with bondo, primed and painted. That was it.
You'd have to sand blast to know if there is enough of the keel flange left to save the keel. Around my area a decent Ranger 26 can be had for 3 -5 thousand dollars.