Custom Firebox & Chimney CAD Design

I need a complete CAD layout for a large outdoor wood-burning firebox and chimney that will slot neatly into an opening I already have. The surrounding structure is concrete. Whilst I am supplying a sketch and photos with dimensions, ideally I would like this drawn by an expert who can optimise/engineer the design to technically correct (or close) dimensions, front opening etc for air-flow, draw etc

Opening in concrete is approx 1055mm wide x 620mm high
Stainless steel surround internal dimensions are 900x400mm

Your drawings should show how the firebox, flue, and any required clearances interface with the concrete, and they must follow standard guidelines for wood combustion (heat shielding, airflow, draft, etc.).

Deliverables
• 2D plans, sections, and elevations (DWG or DXF)
• A 3D model (STEP or similar) I can share
• A brief note on material specs, clearances