I have A 6'x 8' space to work in with an overhead sewer 2'above the basement floor the basin I would like to put by the gravity flow line with the toilet opposite corner of the basin,shower on the right and sink 3'in front of the basin on left wall

HI Zby...

I can probably help you with that, but first, find out if WET VENTING is allowed in your area and then post back so I can see what we can do here, OK?

I also answered your question on the sewage ejector so go check that thread out as well.

Mark