Precise STL-to-STEP Conversion

I have several mechanical part models saved as STL that now need to become fully editable STEP files. Every feature, hole, and surface must carry over with the same dimensions and tolerances the parts were originally designed with—no approximations or smoothing that would alter fit or function... (Budget: €250 - €750 EUR, Jobs: 3D Design, 3D Drafting, 3D Modelling, CAD/CAM)