Came across this reel in my closet. It is rated for pretty much 10-14 pound line. Yes it is a cheap $20 reel. Would it work as a crank bait reel? Or any specific baits? I have a 6'6" medium Lightning Rod I thought I would throw it on.

No reason why not, bear in mind an older size 40 reel may have a bit of weight to it and not balance that well, but that doesn't mean it can't be used.  I would not put a nickel into the reel except to clean, oil and lube on your own.  If my intent was a daily use reel I would opt for a new budget reel, preferably a smaller size.  For some occasional  casual use go have some fun with it.

Sure you can use it, and with a medium power rod, you can use it for a wide variety of techniques. That, of course, assumes the reel is in good operating condition and you feel comfortable with a reel that size.