Convert units and units of measure

I have some data that is currently in a given type of unit and unit of measurement. I need to convert it to a different unit and/or unit of measurement, e.g. 150 grams to 200 grams, or 150 grams to 1kg; or 130 mL to 1L, etc. The unit and/or unit of measurement I need to convert are given to me but I figure there must be some way of doing this without me having to individually modify the formula in each row. Perhaps using some sort of AND() modifier?

I provide an example in the attached with the expected results (if the red colour could be kept for those cells with changes, then even better). I want to go from the 'old data' to the 'new data'. The units that I need to convert in my data are those that I list in this example. There are some odd ones every now and then such as 'box', but these should be left untouched as no conversion is needed.

Any help would be appreciated, thanks.