If you really like the sound of the recipes you found for the 28oz cans, you can also do the math to scale down the recipes to a 12 oz can... i.e. 12 oz is 43% of 28 oz, so you could add just under half of the amount listed for the 28oz can. So, for instance, if the 28 oz can recipe called for 2 tsp of an herb, you would add 7/8th tsp to the 12 oz can... you could just eyeball a shy tsp, which would be even easier.
Just a thought...
p.s. Forgot to add that I agree with Mike... less is more. Whether scaling the recipe or trying a new one, I would err on the side of less... after all, you can always add more. Be sure to let the sauce rest for a while either way to let the herbs infuse into the sauce.