i was wondering if there are any differences in combustion chamber sizes or port sizes, between the 2.4 2RZ-FE head and the 2.7 3RZ-FE head, as far as i know the heads should bolt on the same because the 2.7 is just a stroked 2.4 (2rz has 95mm bore and 86mm stroke, 3rz has 95mm bore and 95mm stroke) or are the heads just identical in every way

 

If I were to bet, the head for the 2.4 will have a smaller combustion chamber. Not that that is a bad thing if you're looking to increase compression ratio for more power. It was a very common swap with the 20R heads and 22R engines a few years back.