UOM Suggestion and Product Bundle

Hello
Our client is a distributor and he purchases items in barrels or drums which have a capacity of 200 litres
This is then combined with other items and repackaged as a retail kit and sold.

Ex:
Car was liquid is purchased in drums of 200 lts
Car polish is also purchased in drums of 200 lts

Retail Kit Product Bundle consists of
Car wash 500 ml
Car polish 500 ml
Wiping cloth interior
Wiping cloth exterior

This is then sold as an unit. The retail kit is crated by a vendor once the items are supplied

I have created a product bundle with the above skus and the

How do we define the UOM and conversion factors for scenario. What is the correct method to implement this in erpnext.
The requirement is to see how many product bundles can be created with with the existing stock of materials and when the order for fresh barrels how many product bundles can be created. The client wants to view the complete
view on the stock position, availability of kits etc

Thanks