to figure out if pushing/folding is +/-ev, follow these steps
1) run chip stacks in icm calculator if you fold
2) run chip stacks in icm calculator if they fold to your push
3) run chip stacks in icm calculator if one of them calls and you win
4) run chip stacks in icm calculator if both of them call you and you win
call those ev values a,b,c,d
a is your baseline
if bp(b)+cp(c)+dp(d) > a, then it's +
for your conditions:
p(b)=.75*.75=.5625
p(c)=.25*X, where X is pokerstove's answer for how 56o does against the range of top25% of hands
p(d)=.0625*Y, where Y is pokerstove's answer for how 56o does against 2 hands that have ranges of top25% of hands
icm calculators:
http://sharnett.bol.ucla.edu/ICM/ICM.html
http://www.chillin411.com/icmcalc.p