This is a very interesting question and I will attempt to provide an opinion that hopefully has some value. In this JV, I am assuming that there is probably one other partner and your company is the dominant partner in the transaction. Additionally, I am assuming that the other limited partners in the JV will have some ownership ascribed to then in your company at the end of the transaction. If this is correct, then for the limited partner they would effectively be purchasing interest in your company using their value in the JV as currency. For your company, they will need to align on a valuation with the other limited partner in the JV, which effectively would resemble activities carried out during the due diligence exercise, with the twist being that all the components are known and the only heavy lifting would be agreeing valuation with the limited partner. therefore in this context yes principles of the M&A framework for DD and Valuation would apply.
With respect to bringing the two business together, I argue that your company will definitely benefit from the Post Merger Integration principles starting with the obvious one which you have stated “Culture”. Failure to gain congruence in the cultures can destroy value from the integration in several ways, including but not limited to loss of key talent or talent pool, culture clash impacting key strategic decision, loss of key customers etc. Considerations for example where certain roles or decision are duplicated in roles, would also translate in potential efficiency gains and consequently the PMI approach would definitely add value.
Therefore, although it is technically not searching and finding a new target that is diligence, negotiated etc, the end game is still the same which is how to execute the marriage of the two businesses to ensure that 1+1 is greater than 2.5.