First let's examine the pot odds. The main pot is $59 or so when you have to call your last $14.40 off. You're getting 4.02:1 on the call. If you assume they both have a made straight and that no one has the nut flush draw you will have up to eighteen outs (one queen, three sevens, three sixes, three fours plus the As, Js, Ts, 9s, 8s , 5s, 3s and 2s.) It is likely that a few of your pair cards and or spades are dead so let's assume you have fourteen outs just to be safe.
If they both have a straight, then we have twelve known cards. The four in your hand, the four on the board, and the four in their hands that will have made their straights. It is possible that one of them will have something like 5s 8s, but since we have already discounted some outs already we will still include those. This means of the fifty two cards in the deck, there are 52-12 = 40 unknown cards left that could come on the river.
Fourteen of those cards will help you, so 40-14 = 26 cards will not. In order to call here, you need to be gettting pot odds of at least 26/14 or 1.86:1. You are getting much better than that so there is no decision to make, call every time. You are very likely to be the favorite to win , and it is most certainly a +EV call (except on the rare occasion where someone else has the nut flush draw).
I don't mind your flop play since that board is fairly harmless.The only cards you can be worried about on the turn are a 3,5,6, 8 or A. I still prefer a raise here since your hand is hardly unbeatable and there are also cards that can come the can slow your opponents down. You also raised preflop so your opponents may push back at you with far worse hands assuming you have AA.
Be careful not to slowplay too often though, as there is not much place for it in PLO. You were fairly lucky here in that the turn card that made someone else's hand opened up a draw for you, and also that you flopped top set with an overpair, eliminating all overset possibilities excluding AA.
Here are the actual odds:
http://twodimes.net/h/?z=1340912
pokenum -o ah 8d 7d 5c - 8s 5s 6d 5h - qs kh ks qd -- 4c qh 7s 6s
Omaha Hi: 36 enumerated boards containing 7s 6s 4c Qh
cards win %win lose %lose tie %tie EV
5c 8d 7d Ah 0 0.00 14 38.89 22 61.11 0.306
8s 5s 6d 5h 2 5.56 12 33.33 22 61.11 0.361
Ks Qs Qd Kh 12 33.33 24 66.67 0 0.00 0.333
You had 12 live outs, which is going to be slightly less than average here because the OE straight flush draw is in there and two of your pair cards are dead. You still win a third of the time on the turn and you're getting better than 2:1 on your call, so it is still a very +EV call. Everytime you call $14.40 here with a 33% chance of winning, you 'win' $9.82 in expected value. Folding would be a big mistake.