To have a balanced system you will need 14-8x16 soffit vents. Your ridge vent has 18 sq. in. of net free area of ventilation per lineal ft. which is 702 sq.in. of ventilation. Divide that by 56 sq.in. which is the nfa of ventilation off an 8x16 aluminum soffit vent and you get about 12.5 I rounded up to make it even on both sides. Hope that helps.
Thanks for the info. Unfortunately with the look of the cedar tongue and groove, I will not be putting 8x16 vents. If i were to cut the vents continuous along the entire soffit, would that be sufficient? The soffit length is 43 feet. So it would be 43 feet by 2.5 inches.