If I recall correctly, H1 wheels will fit on an H2, the bolt pattern is the same (8x6.5in = 8x165.1mm). I believe the hub on the H1 is larger, but that doesn't matter because H2 wheels can be run lug-centric.
If you were going the other way, H2 wheels on and H1, you have to have the hole for the hub machined open more to fit.
There's a thread on here somewhere about this...
EDIT:
http://www.elcovaforums.com/forums/s...6&highlight=h1
Regarding the 37"...if they are 12.5 they will more than likely fit without much (or any) rubbing (it depends on the truck...some do some don't)...tweaking the torsion bars or installing a leveling kit will fix that.