Cost method 02 Vs 08 for actual costing

Hi

Our client requirement is to capture actual cost, without extras for buy and sell items at lot level and client's JDE version is 9.2. One of the options which we consider is to define inventory cost level as 3 (lot/locn) with cost method sales/inv as 02 and purchase cost method as 08. Also thinking about using invent cost method as 08 . Understand the difficulties of maintaining 02 cost method at lot/locn level , without inventory going negative. Not sure about using 08 method for inventory cost method and maintain actual costs at lot/locn level. Any idea about pros /cons