I have searched but am not finding the answer to this question.
I am running Zen Cart 1.3.8a, Database Patch Level: 1.3.8

I would like to create shipping based on the category and then by zone.

For example:
Category A has a flat rate shipping of $12 to USA
Canada Shipping is $20
Contact me for International Shipping

Category B has a flat rate shipping of $15 to USA
Canada Shipping is $25
Contact me for International Shipping

Etc...

How would I go about setting this up the easiest way?

I'm not sure about if someone puts in a product from each category. I might assume the higher shipping would rank? Or would they be combined?

I tried doing this from THIS THREAD but it doesn't offer what I need.

TIA for anyone that can help!
xoxo