Help with tractor identification

I have just discovered I have a 917.2543, serial # 11289.
I cannot find this model on the vintage site, so I really don't know where I belong.
I was told by the person who sold me this tractor that it has the first OHV engine that Tecumseh made. Tecumseh's records do not go back that far. . .
Donald

The earliest production application of an OHV Tecumseh engine on a Roper tractor that I am aware of was on the Suburban line beginning somewhere around 1973.

When I looked up that model number on the Sears parts site (partsdirect.com) several machines were displayed. The only one that I was familiar with was a Custom model tractor. That tractor didn't have a OHV engine as standard equipment from what I remember.

It's more than possible that in the 38 year history of your tractor that you ended up with a new engine somewhere along the line..