I think something that hasn't been addressed is your title of this thread, "future bench rifle". What you've already got would be adequate setup for a bench rifle. When most people think about bench rifles, they think of huge slab, chunky stocks, custom barrels, blueprinted actions, custom triggers, and ultra high end optics. I admit that I fall into this category too. Especially if you talk about shooting 1000 yards, it's even easier to start thinking along these lines. But in a reality a bench rifle can all kinds of things.
The point is, if you hadn't mentioned wanting to shoot 1000 yards, it wouldn't take much to turn your setup into an adequate bench rifle. But when you talk about 1000 yards, there's a BIG step from what you've got to what you need. Nobody here wants to see you sink a bunch of money into something and find out later that your money could have been better used in other ways.
And as far as wanting to be different and use the 8mm, I know the feeling. Sometimes I like to do unconventional things as well. If you're planning on reloading and developing loads for an 8mm, then you might want to look at some other calibers. If you have the equipment to reload, your caliber choice isn't just limited to mass produced common calibers like .308, etc. Take a look at some Ackley Improved calibers and others. I think you'll find a cartridge better suited for 1000 yards than the 8mm and it can still be something that isn't as common as commercial calibers.
