Mechanical HVAC Stamp Needed

I have an existing HVAC layout that is being altered and the local building department will not accept the drawings without a registered Mechanical PE stamp in Minnesota. The design itself is complete;... (Budget: $250 - $750 USD, Jobs: AutoCAD, CAD/CAM, Construction, Construction Engineering, Drafting, Engineering Drawing, HVAC, Mechanical Design, Mechanical Engineering, Solidworks)