If you don't mind me jumping in here (even tho I am an PLO8 guy), I'm not sure if this is really the ideal way to consider playing PLO. When you don't have any hand that is a dominant favorite over any other, getting all in preflop is not (IMO) the way to play. You are not going to be an 8:1 favorite like you can be in holdem. Look at a monster vs. a horrible hand (not sure if there's anything worse, but it shouldn't matter too much):
http://twodimes.net/h/?z=1555571
pokenum -mc 500000 -o ac ad kc kd - 2h 5s 7c td
Omaha Hi: 500000 sampled boards
cards win %win lose %lose tie %tie EV
Ac Kc Ad Kd 354811 70.96 145189 29.04 0 0.00 0.710
5s 7c Td 2h 145189 29.04 354811 70.96 0 0.00 0.290
So you are at best a less than 2.5:1 favorite. Since you're heads up, this is about as good as it's gonna get too. Against a hand that is more likely what your opponent will go to the felt with preflop you are looking at maybe 3:2 -
http://twodimes.net/h/?z=1555588
pokenum -mc 500000 -o ac ad kc kd - 9h 7h 6s 8s
Omaha Hi: 500000 sampled boards
cards win %win lose %lose tie %tie EV
Ac Kc Ad Kd 299780 59.96 200220 40.04 0 0.00 0.600
8s 6s 9h 7h 200220 40.04 299780 59.96 0 0.00 0.400
To be honest, neither of those appeals to me when considering pushing in preflop. In fact, nothing could appeal to me enough to make it something I'd want to do outside of a tourney situation where I will need to take risks like that. In THAT case, then numbers like those are good to know.
The cool part about PLO8 (for me at least) is that it's more of a post flop game than holdem. The stats that (again, IMO) should matter are how your hand will hold up on the various flops you'll see against your likely opponents holdings. Monk made a good point in another thread about how a nut low/nut flush draw is a slight favorite over top set in O8. That's (to me at least) the kind of numbers that really matter.
Of course, that's just my opinion, I could be wrong...