I am wondering what implied odds I think I should be getting preflop to enter a hand with connectors (say 89o).

I'm not great with the math, but here are some of my thoughts.
The odds against me floping 2 pair, trips, str8, full-house, or quads are about 20:1
I could also flop an open-ended str8 draw. I think this gets me down to about 5:1 to flop a str8 draw or one of the above mentioned hands. The problem is that if I flop an open-ender, I will only complete the str8 31.5% of the time (assuming I have sufficient odds to call the flop and turn). I think this gets me down to about 10:1 that I either flop a good hand or I flop an open-ender and complete the str8 by the river. The problem with using 10:1 as my number is that while I complete the str8 31.5% of the time, I miss the str8 68.5%. When I miss the str8, I've invested additional chips which increases the cost of playing this hand.

So I ask, what odds should I be looking to get to call preflop with a hand like 89o