Basement Bathroom DWV design Sanity check

[jeromio]

I'm redoing an ancient basement bathroom/laundry room. The current setup has a long sweep 4in cast iron elbow dipping under the 4in slab and connecting to the city sewer right at the outside wall. The lateral 10ft of 4in (now PVC) is up at high 78" across the room. The new design will remove that cast iron 90 and instead bury the lateral 12ft under the slab. The problem is that the top of the cast iron exit pipe is only 7in from the top of the slab. Unfortunately that main line will be exactly where the toilet needs to be set. I *think* I have enough room to put a 4-3 PVC combo on its back for the toilet. There will be mortar and tile which gets me another 0.5", but I may end up having to pour an inch or so of cement to raise the floor - obvz would rather not have to do that.

I think I have the vents sorted out and sized correctly. I plan to do a studor vent at the lav. The outer walls are masonry. I'm hiding a dry vent for the laundry in the powder room wall, running laterally thru the ceiling to tie to the 3in vent stack for a bathroom on the main floor. The shower I'm hoping is sufficiently vented by the 4in "wet vent" that is in turn vented by that same 3in stack. There is a 3 by 1.5 san-tee just above that 90 that goes to a tub. If I have to, I think there is enough room for a 45° angled san-tee under the floor there to do a vent in the wall. If I have to raise shower floor to accommodate, that's not as bad as the whole bathroom.

Any and all feedback welcomed, thanks. Here are some drawings: