How many stages of scavenging?? We have run a dedicated stage to turbos before but have never tried to share one. I only have 2 stages of scavenge on my current engine and I run both turbos to the front of the pan above the oil level and let the pump only pull on the pan. I also run a vacuum pump which I hope will help with oil return from the turbos as I do not have a lot of vertical drain back to the pan. Hope this helps.
It would probably be ok run with one of the stages at the front of the pan especially since it is a BB turbo and chances of over scavenging is not really a issue. I would just check it frequently to make sure it is not forcing oil past the turbo seals to be sure it is draining properly.
The thing that has worked best for me is building a upside down "T" at the bottom of the turbo. I put -12 male fittings on the end of the T and the base of the T is the turbo flange. Hook one side of the T to your oil pan scavenge port, the other side to the dry sump. This creates a drop zone under the turbo that has constant flow.