Good morning Tom,
I'm very familiar with Inventory valuation using FIFO/LIFO/Average/Standard costing methods. I worked with several accounting systems from Real World, MCBA, Maccola, and now Pass-Port Software. I used to have the source code for the Inventory Control module from Real World. This was coded using COBOL... yes, I know this is supposed to be a dead programming language. But, it is still in use more than 40 years later.
I now own a brewery and have been utilizing Front Accounting since 2018. Unfortunately, I haven't been using the Purchasing, Inventory and Manufacturing modules primarily because it doesn't support FIFO.
I do know some PHP coding as well but the Object Oriented concepts are foreign to an old "Top Down", "Structured Design" COBOL programmer. I would be willing to take this on if you are willing to help with the PHP coding.