Hi me...( hmmm)
I've been doing projects like this for years, sometimes successfully, sometimes not so.
I first have to establish a value for my time. It takes some research and discipline, I'm kind of a project junkie.
So I have to get clear with myself about my intentions.
I just completed a 2 year design series, starting with sketches, blueprints, proof of concept models and then masters and molds. There were running changes so the time for reworking the design had to be factored in too.
Engineering is also a necessary component, whether you or a subcontractor are responsible, these costs can get out of hand quickly. Your contract must address such changes, who caused them (the principal or you, and, or, did engineering take it upon themselves to alter something and were proper channels used.
Overall budget is also a major factor in the distribution of funds, where are you in line with the distribution of funds and by when? Is there sufficient funding, and commitment, to keep the flow of work moving and the subcontractors engaged so the project is the first priority.
How many people are involved in the decision making process? Design or approval by committee brings up a host of unique scenarios, usually at the cost of your time.
Is this going to consume all of your time?
Will you be putting off or deferring other clients while you're on this project? Will they be willing to wait or come back later? A big short term win doesn't always play well for the future if people feel they haven't a sufficient priority to be treated equally.
There is certainly more here, and, I hope I have not complicated what wants to be an easy answer.
My best wishes for your success. I am very interested in the comments of others who have experienced this opportunity .