Single VM template with multiple catalog entries with different resources sizes?

I want to have 3 Blueprint sizes: 

• Large - 4 vCPU, 8 GB mem, 120 GB disk
• Medium - 2 vCPU, 4 GB mem, 80 GB disk
• Small - 1 vCPU, 2 GB mem,  40 GB disk

But I do not want or need 3 different base Windows 2012 templates (pain to maintain)   I want to have 3 unique catalog items that deploy the same vCenter template but with the different resource sizes.   What is the easiest way to do this in vCAC?   I am assuming I need to do this via VCO?

Thanks,

-MattG