If 91/135 combined is 300 hrs, 125k for the Manager/Pilot sounds reasonable. But if you think you can truley crew it with just 2 salaried pilots, good luck. Having two salaried Captains and a pool of part timers (@$3-400 a day) will be more realistic for your budgeting. Trying to crew part timers for 135 is another story. Keeping part timers for just the 91 flying works better.
I guess what jumps out at me is the 2 pilot scenario. 300 hours is not alot, but it is always a the wrong "life moments" with just 2 pilots. Owners don't like to hear about Pilots having personal problems when they want to fly.
Good Luck.