This is definitely a raise spot with this many opponents in the hand and the bet already made is that small. We want to protect our hand but also build a pot and create value for this street and future streets. Sixing of $2 seems like hitting the nail on the head imo but I think it should be at least $1.60 and probably no larger than $2.40 unless you know there are some stations at the table. $2 just seems like a logical bet since it is 4x over the initial better plus an extra 1 for the caller.
Your question regarding if SB raises, is that asking if SB raises the 40 cent bet before it gets to you or are you asking if SB raises our $2 bet? If it is that we bet $2 and then they raise us then (unless we have a history with them and they believe we raise any flush draw) my thinking would be they also have 8x which we are splitting with (beating 6, losing to 5, chopping to 1 without getting technical with combos) and then it comes down to how loose SB is since if they are not that loose then they will not overcall the HJ raise with 82, 83, 84 anywhere near as much as they would with A8 or K8. If the question is regarding what if SB raises the 40 cent bet before our action then what do we do? I think I would be raising that bet since even though we have a value hand right now the board is wet and I would be too scared (whether that is right or wrong is definitely debatable) to just call and then have the two others call as well based on price and then set ourselves up to be potentially drawn out on.