I haven't converted in this direction (only 3.5 to Iron Heroes), but the balance should work in theory. Iron Heroes classes and Pathfinder classes are both trying to hit about the same balance point (3.5 casters).
That said, I'd be pretty leery of doing a straight conversion to Pathfinder. A quick and dirty conversion for NPCs shouldn't be too hard, but you might end up having to do new class write-ups if you're allowing PCs to join the classes.
One thing you will have to look out for is overvaluing magical damage. Since magical damage in Iron Heroes ignores armor, even small amounts of it are useful. The simplest conversion is probably to just set any magical damage requiring an attack roll to touch attacks.
Converting anything involved reserve points would be also be weird. I'd suggest granting temporary hit points as a decent stand-in for healing from reserve points and converting damage to nonlethal damage for anything granting additional reserve points.
HP and skill conversions are pretty easy. You'll have to figure out what to do with the class defense modifiers... I'd probably leave them in place.
That's all I can come up with offhand, hope it helps!
Cheers!
Kinak