Wait for the part from McIntosh.
If "any" transistor will do, I would expect Mc would have filled your order by now. Weather be tightly spec'd or proprietary there is a reason for the wait.
I personally would look up the transistor on Mouser, Digi Key, Ebay?... and go for it, But I do the work myself and take the gamble.
Don't tell the tech to go look for another place to get the transistor. Unless you are willing to pay him his hourly to do it. If you get the part and he installs it. He's not going to warranty the part. You take the gamble, No guaranties. With the OEM part, there's better chances everyone will be happy.
Color Coded?