That appears to me to be an original sporter. Mine has been gone for some years now, we were discussing these a year or so back. The grip cap and grasping grooves suggest original sporter. The sights too, a Winchester semi Buckhorn type rear sight...Sheard type front... Very nice. Mine went through some hard times and I had to have a stock ,made for it. Had nothing but the back end to work with. The ammo was about $3 CDN each here some time back. I haven't bought any for a while. I had some boxes too but they were hard put and not worth anything. My brass went with the rifle as you can imagine.
There are a few advanced collectors here that I hope will jump in for more definitive info.
Go to this site to compare yours, I think it's good...
Winchester Lee Straight Pull 236 USN for sale