As a 3rd party without detailed knowledge of the space and each company's position it's hard to say. Here is a possible framework for you tho.
Since you are basically asking for co-founder level equity in the merged company, pretend that you were working there the whole time when you were working on your own startup. The acquisition cost is the amount of salary you would have drawn.
Since you are basically asking for co-founder level equity in the merged company, pretend that you were working there the whole time when you were working on your own startup. The acquisition cost is the amount of salary you would have drawn.