Looks good. Thinking things out before hand always pays off.
Don't know if it fits in to your plans but wouldn't having the intake coming in at the bottom be easier? I was thinking you might lose fan pressure and grow room space running it in from the top.
Turtle is right too. Sometimes you find good cheap materials you can incorporate without extra cutting etc. Sort of building it based on standard materials and ideas rather than a definite plan. All my ideas are in my head and 'usually' well thought out. Then I go to the hardware store and it all comes together from there.
Don't know about your growing experience but I would recommend hydro over soil. Go that extra mile and plan a basic hydro setup as well. Initial setup cost will be a little more but it should simplify and maximize this grow and future grows.
Sorry.. Couldnā??t help but notice and say something : Iv = I've (I have)