in general you can see in the movement itself how the total quantity and value of valuated stock was before the movement was posted. this is an important information trace the development of the price, value and quantity at any later point of time.
Fields in MSEG: LBKUM and SALK3
If that could help you for your report ...I dont know, especially with own developments different approaches to reach the same goal are possible.
If you want to make use MARDH table, then read this document to understand how the data is stored in this table: Material Stock and Valuation History tables - how to read them