Here is what I would recommend modifying or replacing if you're removing an EZ30 for any reason:
Cut down the bosses on the timing chain cover and use shorter bolts, gives you a lot more clearance at the lower radiator hose. (see above)
Clearance the timing cover around the upper water necks so you can fit any hose and hose clamp on there.
Check the coolant fittings under the thermostat. (see above)
Check the oil pressure idiot light wire, I think it's above the oil cooler. Mine was hard and insulation was starting to come off so I replaced it. Might be something you can get from the dealer at a reasonable price.
Replace the valve cover gaskets and oil cooler o-ring (orange), these seem to always leak.
Inspect all hoses, many of them will be rock hard and break when you remove them. (see list below)
If you have a manual trans inspect the fork for cracks, check the release bearing, pilot bearing, and clutch disc. The FSM has a spec for wear on the clutch disc. If you don't expect to have your engine or trans back out for a long time at least replace the release bearing, pilot bearing, and clutch disc.
All the parts I ordered from the dealer for the H6 head gasket job are listed below. They do have a gasket kit but it includes a lot of things you don't need or won't be disassembling and it's $271.
1 10944AA003 head gasket 2002 OB driver H6
1 11044AA603 head gasket 2002 OB passenger H6
1 806931070 o ring rear cover plate 2002 OB H6 - did not use this, didn't seem to be leaking.
1 806786040 rear main seal 2002 OB H6 - did not use this, thought it would be more hassle than it's worth trying to get it out without splitting the block.
2 14035AA410 intake gasket 2002 OB H6 (head to intake)
1 14075AA132 intake gasket 2002 OB H6 (gasket for flapper under intake, probably didn't need to replace)
1 807611060 pass side coolant hose 2002 OB H6 oil cooler
1 99078AA110 pass side coolant hose 2002 OB H6 oil cooler
1 807611071 driver side coolant hose 2002 OB H6 oil cooler
1 21328AA053 steel coolant pipe lower 2002 OB H6 - this was kinda beat up from my skidplate
1 21370KA001 oil cooler o ring 2002 OB H6
1 807607251 Top rear pass side coolant hose 2002 OB H6 - this was the only hose I replaced that was still in good shape
1 99078AA090 Top front pass side coolant hose 2002 OB H6
1 99078AA120 Top front driver side coolant hose 2002 OB H6
1 807615030 oil pan front driver side hose 2002 OB H6
1 806970030 o ring water pump 2002 OB H6 (inner, included with new water pump)
1 806982030 o ring water pump 2002 OB H6 (outer)
1 21110AA360 water pump 2002 OB H6
1 21200AA072 thermostat 2002 OB H6
1 21236AA010 thermostat gasket 2002 OB H6 - still the part shown on the dealer parts site but the part I got ends in 050, seemed to fit fine
1 21114AA063 water pump gasket 2002 OB H6
8 806914120 o ring 14.2mm dia 2002 OB H6 timing cover
2 806919120 o ring 19.2mm dia 2002 OB H6 timing cover
4 806925100 o ring 25mm dia 2002 OB H6 timing cover - only shows four of these on the dealer parts site but there are five on the engine, reused one of them
1 806738200 front main seal 2002 OB H6
2 10982AA000 Washer 2002 OB H6 (timing cover) - these were really stuck to the cover, I just put silicone around them
1 15208AA031 H6 oil filter
5 800406020 oil pump bolts
2 800406030 16mm outer cover bolt
1 16102AA260 solenoid valve - the one I broke the fitting on
2 44011AE040 ex gaskets 2002 OB H6
1 807506131 hose pass front intake/head
1 22310AC000 hose driver front intake/head
1 99071AB280 hose vacuum
Also probably should have ordered that oil pressure relief gasket shown above.
There was at least one more hose near the front of the intake that was rock hard and broke when we removed it that I couldn't find on the dealer parts site so I just cut a piece of hose to fit.
I also got idler pulleys, a serpentine belt, spark plugs, and a pilot bearing from Rock Auto and replaced those while it was apart.
Even if you didn't replace the water pump and a few other things and don't break that solenoid, it's still $400-500 in parts with shipping, and you have to machine the heads. So almost definitely better to just buy a JDM EZ30. It takes a long time to disassemble and reassemble one of these engines, and we didn't even split the block. Really should have just swapped in an EZ36 and standalone from the start. Next time.