I'm closing on my new project in 2 weeks, and was planning on financing the rehab, however I realized that I have an old IRA that could fund the build out.

How can/do I structure this? Self directed IRA? What are the details I need to be conscious about?

I have very limited experience with self directed IRA/solo 401k. I didn't really know they existed/ were actually utilized until spending time on BP.

Thanks in advance as always

It's probably too late on this current deal. You probably have it under contract in your own name. Moving it to an IRA at this point would be self dealing. Not to mention you'll never get the new IRA set up in two weeks.