Loft irregular surface to cylinder

[priyanairQQM4M]

I am working on creating a model of a blood vessel for 3D printing. In order to be compatible with connectors for tubing we will be using, I want to create a extended and enlarged portion of the vessel. The edge of the vessel inlet is flat but an irregular shape. Is there a way to loft to a larger diameter and in a way that the final surface will be a concentric circle (cross section of a cylinder) while keeping the surface smooth? 

Attached a screenshot of what I'm picturing it to look like.

Thanks!

[hfcandrew · Accepted solution]

Yes. Select the bottom couple of millimeters then > Modify > soft transform

[priyanairQQM4M]

Thanks for your quick response! Is there a way to prescribe the final diameter of the extended portion instead of a trial and error with the transform?

[hfcandrew · Accepted solution]

Yes, click on the S to turn on snap step, then you can warp it by the millimeter