The stock Jets on a 670 Street Avenger are 65 primary and 68 secondary , I would try the 68 secondaries Jets in the Primary side (since you have them already) they might be a touch to Big , may be 66 / 67 will work better , and the secondaries try some 71 / 72 and see what happens , on the Street Avenger the Gaskets should be re-usable.