Yep without the mission profile it’s all guesswork.
As always with older aircraft as you well know it’s the hidden things during checks that catch ya. Corrosion for one.
There was a thread on here somewhere about an SP being sold parted out.....
The legacy is great as mentioned, cheaper to purchase, as it’s common to the 135 as said the ratings and recurrent cheap. Bit like a BBJ/ACJ ratings and renewals a slight of the cost of the corps, economies of scale.
Sounds like a great adventure and as the boss already understands aviation with the right advice the right machine won’t be far away.