I have a 50 year old ranch with 2 full baths (A and B), one of which I have gutted and am remodeling (B). Bath (A) has a 3" copper waste line for the sink, toilet, & tub and vents thru a 3" stack. This same waste line runs about 15 (linear) feet where tub (B) ties in and the whole thing empties into the cast iron main drain. There is a second 3" waste line for the sink and toilet in (B) that is vented by a second 3" stack. This line ties into the cast iron main drain about 4' above the one from (A).

Originally, the 3" vent in (B) ran thru a closet wall and was at the end of the run. That closet is now gone. I removed all the fixtures and the 3" vent pipe and reconfigured it as follows: I connected a 3" wye (with a 2" branch) to the cast iron main with a rubber clamp-coupling. I will run 3" PVC to tie in the toilet and sink which are 3' apart and 18" from the wye. I replaced the 3" copper vent with 2" PVC coming off the wye and going up thru the attic to the roof. Here is my question: is this enough venting for the sink and toilet or did I make a huge mistake by using only 2" pipe? I figured the other vent was already handling the other fixtures and reducing vent (B) wouldn't really make that much difference. I haven't sealed up the walls yet so I can change it if I need to.

Please let me know if this is OK. Any/all advice I can get would be greatly appreciated.