looking for some recommendations for a stroker

4.11's behind a stroker aren't real street friendly unless your running 30" tall tires. Strokers don't need low gears so you may want to reconsider them. And I'd bet that converter will stall over 4000 grand behind a stroker. Remember, the more torque input to the converter the higher it stalls

The single plane and 850 sound good for a hot stroker with W2 heads as long as the cam is big enough.

As for the brand of carb I have always liked Holleys but lately have used some Quick fuel products with great success. Their an offshoot of a Holley like many others but they have some improvements in certain areas. Never ran a demon so I can't say anything about them but if I've heard Demon's are wet flowed so an 850 demon is more akin to a 900+ cfm Holley.