2000 2.7l 986 Coolant & Exhaust Gas Intermix

[maxgestic]

Hi everyone, looking for some advice.

I bought a beautiful year 2000 986 with the 2.7 engine.

Recently i had a mechanic diagnose that my coolant is mixing with exhaust gasses.

Now they said it's most likely a crack in one of the cylinder heads.

Could there be any other way that exhaust gases are getting in the coolant and if so how would I diagnose this without tearing the engine apart.

Just looking for the most financially sustainable way to keep this car running as I really do love it.

Can I just buy a a replacement head and slap it on there and hope it works? Or does it have to be the exact same part number and year?

Mechanic recommended to just drop a 3.2lt "S" engine into it as apparently they don't have this issue as much. But they are quite dear tbh and I don't know if it's a straight swap either?

What's everyone's advice here?