"If it's a 58" bow that's shaped like a new model Grizzly, then it's a 1967 bow (the first character "7" in the serial number denotes 1967. I believe this dating method only applies to Bear bows made from 1965-1969). Bear made 56" Grizzlies for a couple of years, I think in late 60's or early 70's, but the vast majority of Grizzlies are 58". Older Grizzlies, up through 1963 I believe, are 62" long."
I found this in an old thread. If correct Id guess it'd make yours a 1969 since your first number is a 9. I could be way off though, but it looks right. For the limb twist... You can find a lot of options by doing a search, but I'll offer some help, take it for what it is..
1) Always use a stringer
2) unstring the bow and run the twisted section under warm water for a bit.
3) counter-twist by hand and hold until it cools
4) repeat as neccessary
5) restring and hang by string level
I've never had a hard time untwisting a bent limb but I suppose I've never had to do a super bad one either. Some say heat gun, some say hairdryer, some say no heat. Warm water seems to be a happy medium thats been successful for me more than once.