Ah Mike dont you just wish plumbing were that simple guy?
Venting is not just fixture units connected BUT developed lenth of pipe and fittings.
For example I could run 8 FU’s on an 1-1/2 line BUT only for 30 ft BUT I would need a 2″ line to go up to 170 ft.
Did you now depending on what type of toilet you have how many fixture units it is rated at?
For example a close couple tank and bowl would be 4 FU and a flushometer type would be 6 FU..
Why dont you invest in a local code book rather then guessing?