Bypassing old plumbing by tapping into main drain in house
I am considering abandoning a 1.5" drain that services my kitchen and laundry tub. I've had problems with it draining and after snaking and extracting some interesting items without solving the draining problems I suspect it might be better off trying something else.
http://img709.imageshack.us/img709/5117/97516612.jpg
I can't get the cheap Home Depot snake into the bottom of this drain, entering through the pvc section on the left, it barely makes the first curve and I don't see it being possible to make the next one. Given the age of the house (75 yrs) and condition of the pipe I'm not sure it's worth bringing in a pro to hear I have to dig it up and replace or something.
I'd rather start up the kitchen...
http://img525.imageshack.us/img525/2999/60789441.jpg
Sever the steel drain about 4 ft or so from the floor and connect it to new 2" pvc running down into the basement in it's place. Can the remaining 1.5" pipe that vents up through the ceiling about 5' out of the picture serve as a vent for a 2" pipe?
http://img694.imageshack.us/img694/9025/23302073.jpg
I'm curious if it's okay to run the new 2" PVC down into the large open cleanout in the above picture into the main drain.
This would leave me without a laundry tub drain, which seems like a bit of an issue. Any other thoughts or guidance would be appreciated.
Thanks!