Historical costs in WIP for std and actual cos

Hi;

I have a requirement to calculate the actual_cost and standard_cost for a specific assembly.  Now the report must consider the historical costs as well, meaning depending on the period Im running the report

the relevant unit_cost must be considered as well.

To give you an example.  The Item ,eg bread is made up of different components(flour, ingredients etc) so I need to calculate the cost on bread as well as the component level.

Regards

Trevor