Head question on 6.5 with 6.2 block swap

Hey guys, Im new to all this stuff but I have a 1997 K3500 with a 6.5 that started eating antifreeze so we pulled it apart and saw the cracks in the block, but the 6.5 heads were good. A solution that presented itself was to use a 1984 6.2 block and just install the 6.5 heads and Turbo etc.. I ended up having a mechanic do the work and he kept the 6.2 head on the drivers side, but changed out the 6.5 head on the passenger side to clear the turbo. This goes against my common knowledge of changing heads but is it a real problem? BTW its now throwing P0266 and P0272 codes.

Any help would be appreciated.

Thanks

Others can weigh in on the technical issues, but I’d not want to run an “uneven” configuration like that.

The heads are of different design, in more ways than one (the 6.5 head used for turbo installation, for example). Many other issues will crop up, such as cylinder imbalance (the DTC's you are seeing), as well as other long term concerns. Which set of injector lines were used? You can't (successfully) mix/match nearly any of it, including the heads as a whole. Poor choice by the mechanic.

Use matching heads, this is important!