the eg33 is just an ej22 with 2 extra cylinders added to the front. so it is considerably longer, the crank pulley will sit where the rad does. when i did my swap i had to move the rad about 2 inches forward.
the ez30 was an all new design, they designed it to take up roughly the same space as an ej 4 cylinder. it uses a timing chain instead of a belt. early ez30 had 1 exhaust port per head, and there is a swap header available for it. this is probably the easiest of the H6 swaps. the ez30r has 3 exhaust ports per head, and is just as easy to swap in as the early ez30, the wiring is where it gets difficult because of the immobilizer. you either gotta go full standalone, or be really creative with the factory wiring.