I just use Odds Oracle, available at
http://propokertools.com/ which is free currently. Though I do own the paid version.
Doing drawmaha ranges in an omaha calculator is annoying. I think villain has very few traps given how short and whaley he is, so I think his range is going to have a lot of small and medium 1p hands, and also 1 card flush draws (also maybe 2 to a flush draw). He might have some aaxxx and two pair combos too, but i think we should discount those.
But to give some simple equity example for the omaha side:
If we give Hero a range of KKxxx, and villain a range of AAxxx, QQxxx - Hero has 82 % equity
Against QTxxx, Hero has 66%
If Hero keeps the QT vs QTxxx: Hero has 77%
the more small pairs we add to villain range the worse his omaha equity becomes, which is how i arrived at my 85% equity - which could be too high, but upper 70s is certainly reasonable
still without seeing villain's hand, i think draw 3 is going to be the best net equity play when we account for the equity improvement in the 5C-High