I hope it goes well, personally I would have waited for a few weeks (at least) of testing. One of my biggest points of advice to anyone trading is don't ever rush into a trade, once your capital is gone, its gone. Who cares if you miss a big trade or too, if the strategy is sound, you'll have another.
My list is at my office, but sure, I can share it when I go back in on Monday. As to how I got it, I used a publicly available option screener to list out the most volatile options with an underlying valued over $25 (ended up somewhere around 150 names). I took that list and entered each name into TOS and looked at the OI and trading volumes. Anything under 1K OI+Trading volume automatically got booted --- my list was still a little too big so I knocked off the lowest 50 OI+Vol stocks. That gave me a list of around 40 or so. Nothing that scientific or complex too it, just a working place to start.
But 3.37 credit is not your margin - the margin is 5-3.37=1.63. This is equivalent if you did it with calls and puts, paid 1.63 and sold at 2.24 (5-2.76). So return on margin is 37% (2.24/1.63 in case of debit transaction or 0.61/1.63 in case of credit transaction).