[gojomo]

Trying to put a "60h/week" commitment into a contract is unwise on many levels:

It's trying to measure by clock-watching something inherently qualitative rather than quantitative.

Most people can't be productive and efficient with that kind of sustained time-on-task, for more than brief crunch periods.

And, if they're a co-founder, you need to trust them, and be setting mutual understandings, at a much deeper level than some contract.

Your jurisdiction's law may (and probably does) differ from the US, but if there's some process by which he (or conversely you) can be let go if things aren't working out, and thus any payments or vesting stops, then that's your elastic all-purposes way to deal with someone's failure to meet expectations. Writing down some unrealistic commitment metrics can't replace the kind of deep mutual trust and shared mission you'll need.