What to look for when buying an engine.

Found out today that I might actually get approval for a newer engine as well 2008+, so might be looking at one of those.
Only issue is that they would require an upgrade to larger brakes based on the following formula:
Rotor diameter = 260+ (0,3 x power in kW) + (axle load in kg – 1000) x 0,05
So I would need 12.5in discs up front...
Started a new thread for the brake upgrade... Although good brakes are cool, it seems a bit over the top?