It is not clear to me what you are trying to accomplish. A horizontal vent needs to be above the flood rim of the highest fixture served, but your drawings show a vertical vent.
We would need to know what size and type of fittings are being used to determine if if what you intend to do is right or not.
In most of the U.S., you would be required to be a licensed plumber to perform this type of work in a structure that you do not own. I don't what happens north of the border.