im putting my spare together with the parts i have laying around 850 also, gonna be 80 primary with 4.5 power valve and 84 inthe back probably with a 4.5 power valve to jet it up my motor is far from stock and i have a victor with a 2 in spacer and a n20 plate a lot of rise there if my new combo is to rich i will swap it out thats why i test and tune.