In general, are there restriction on using SDIRA on a development/construction project...we have a first lien balance around $80k and reno should be $250k.

One of the big steps you should undertake is a review of what kind of seller you are dealing with.

It depends on the deal and structure; my hard money lender is willing to lend up to 90% of purchase price and 100% of construction costs. 

Remember, real estate investing / construction / this industry as a whole are about building relationships, so treat people with respect and those relationships will grow well. 

We buy at a deep discount and usually acquire with a loan product that allows us to roll in construction costs. 

I have a construction background so the hard labor of the rehabbing is what I look forward to the most.

We are watching all the new construction going on and know the land will be worth more in the future (and rent is higher because of the land) but right now it doesn't make sense to lot split and build due to the sky high costs.

If you are getting a loan you can pack in the construction costs to your loan, called a "construction loan". 

The only concern I have about new construction is the new property tax value when completed.

I am currently in construction management and the wedding entertainment industry.