In my travels I found someone with a gravely tractor with the sulky and attachments 1963 with electric start which I thought was rare.Anoyone looking for one if you want it I think he will sell it.
I had one that I inherited from my grandfather. It had a 48" mower deck, a 36" brush hog- with one set of field blades and a set of 1/2" thick brush blades- and it also had a vertical shaft tiller. It also had the electric start (starter/generator) and the sulky. It was an amazing machine, especially with the brush hog attachment. In terms of production vs. investment, it's an excellent machine. I'm sure that at 50 years old, the machine that you found still has a lot of life left in it. If I was anywhere near FL, I'd be interested.
My friend rebuild the wisconsin engine on it ,Runs like a dream .But alas his shop is full of projects and they need to find a new home.