I know very little about the 35's but do know the early ones had wide scope rails compared to the more recent ones & if your piston seal is leather I'm guessing it's an early one, if it has scope mounts already fitted they should be for a 1" or larger 30mm scope tube & either will be fine as most modern scopes will fit depending on make / size etc. I've got 3 35's myself that need a refurb or more correctly worded I'm hoping to make one half decent one, a rougher one with what's left & have a few spares, sadly one stock is cracked beyond repair. Enjoy your plinking.