No - you only need to give the first $100 availability from the combined local and non-local items deposited by the customer on any one day. The fact that you normally give next day availability to a local or non-local item doesn't require you to give even MORE availability.
On your hold notice, you should list the combined total of the deposit ($1,000) and then show that $600 will not be available until ______ (give the # of days or date) In your scenario, of the $1,000 local/non-local items, you are making $400 available the next day - clearly more than you are required.
HOWEVER - if the payroll check is by Cashier's Check, Teller's Check, Treasury Check, Postal Money Order, etc., then you WOULD need to make $100 of that personal check available the next day.
Regulations are a poor substitute for ethics.