Shorty I can understand your frustration but I was faced with the same predicament (ie. no plans to work from). I asked (and still do) Brad heaps of questions before starting. But ultimately I wanted to build my own frame and just sat down and thought about it for a long time. Given your skills and the skills available to you I would suggest you do the same.
I have a friend up in Burpengary, Andrew who contacted me after seeing my website and asked if he could use my subframe design to work off. I readily agreed but ultimately said I couldn't furnish him with plans. In fact I don't think he ever asked for plans just went off the photos on my website. By doing this I think I remove myself from any responsibility for his design as I haven't supplied any details.
Before I started this I had never held a welder or worked with steel. If I can sit down and create a subframe (of which I am proud) then I think anyone can, including you. I understand you don't want to reinvent the wheel but the possibility of litagation is real. As for selling the car, this is why they have to be engineered. The engineer carries personal indemnity insurance running at $10M usually. If they certify it then and legal action afterwards is directed to him not me (theoretically anyway).
Anyway I have attached a sketch of my subframe (which isn't quite accurate but its something...

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225hp atw on 14psi. 1/4 Mile no idea. Take one 1971 Mini Clubman, one Starlet GT Halfcut, Simmer over a warm MIG Welder, and Voila Minstar!
www.mpdesign.id.au
