What's a fair game between a 700 fargo and 600 fargo, barbox 8 ball?

[sparkle84]

Those are big spots to give a 650.

I think barbox 8 ball on a valley definitely narrows the spot between players. I'm nobody and I've broke and ran 12 racks in a row.

650??? In your OP you said 700 vs 600. Without knowing the players it's pretty difficult to assign weight. On a 7 ft table I'd be inclined to give a bit more to a shotmaker and a bit less to a strong position player. Table aside, a shorter race favors the lower player and longer the better player.