Limit Draw: Draw in Blind Versus Heads Up Raise?

[Al Mirpuri]

Five handed draw: 50c/$1 blinds at $1/$2. There is a raise and I am heads up all of a sudden in the big blind with either a four flush or open ended straight draw. The pot is offering me 3.5 to 1. What do I do? (I think inside straight draw an easy fold and inside/open straigh flush draw an easy call.) Please advise.