You would need a 599 engine for starters, unless you want to spend even more money and time.
As far as is it worth rebuilding the existing engine...........what is wrong with it? Did they say why it needed a rebuild?-- it may be far cheaper to buy used up front, but then you also have zero idea what you are getting too....
But if the existing engine has catastrophic failure- you will have no choice but to start with a used engine
Are you a good mechanic and can follow a service manual and have good tools? Or will you be paying out of pocket for most of it?
As far as is it worth rebuilding the existing engine...........what is wrong with it? Did they say why it needed a rebuild?-- it may be far cheaper to buy used up front, but then you also have zero idea what you are getting too....
But if the existing engine has catastrophic failure- you will have no choice but to start with a used engine
Are you a good mechanic and can follow a service manual and have good tools? Or will you be paying out of pocket for most of it?