I really like those old Grizzlies. My limited knowledge base starts in 1959.
1959 - 1963 are 62"
1964 - 1967 are 58"
1968 - 1970 are 56"
1971 - are 58"
I have never shot a Super Grizzly, and look forward to that opportunity.
I can say that the newer ones I have held have a much higher shelf than the older ones (especially in the 1960's).
Shoot what you enjoy and enjoy what you shoot.
I put hundreds of arrows a week through 50+ year old Grizzlies with zero concern. If the bow is solid it will out last me I think.
Enjoy those Grizzlies! You will be very hard pressed to find a quieter bow than a 1959 Grizzly, but there are so many good Grizzlies across the years.