Looked at your web site. Nice.Cheers!
The parts cost estimate is in the ball park. I spent $20,000 on the Sprinter conversion. Have spent $12,000 on the Transit conversion so far. Only major item still to spend on Transit will be the fabricated stainless tanks and parts. So expect to spend about $15,000.
Second comment: Your 325 man hours to complete the conversion is very low unless you are a significantly better/faster craftsman than I am.
My Transit conversion web site: