PHP function for Wordpress All Import (wpallimport)

I’m using WP All Import to import a list of prices, but I would like to customise the imported price using a PHP function, using similar code to this example [login to view URL] Here’s what I need to do… If the new price column (in my data file) is 0 then use a different column of data (in the same file) If the new price column is not 0 then the new price would need to be multiplied by 1.25 Then If the SKU of a product equals a certain value (there’s around 50 items) then the price needs to have an additional £7 added to it. Please note, this is an older version of the Wordpress and the All Import plugin (it does support the PHP functions mentioned) we are unable to update. Also the site import is large 16,000 lines - so it will need to be fairly efficient code (as we want the import to run over the night).