I'd probably just trade him tbh unless the team plans to be really really aggressive in free agency this upcoming offseason. We have a shitload of holes and he'll be on the wrong side of 30 by the time we are any good.
That said, if I were to extend him I think 5 for 80 is the absolute max I'd do. Anything more would be too much and anything less I'd be pleased with. And this would include his final year of arb next year which would be ripped up.