How to know if a recipe is acidic enough for storage/bottling?
Excellent question! I understand wanting to experiment with your own recipe. I hate following recipes and would much rather develop my own. 

Virginia Tech has a PDF file that I consider invaluable to download at Boiling Water Bath Canning. In the downloaded file it says 


  Only high-acid food with a pH of 4.6 or less can be processed using the boiling water bath method. This is because only high-acid foods  prevent the growth of spores of the bacterium Clostridium botulinum which can't be killed by boiling. Foods with a pH more than 4.6 allow the spores to grow. 


Everything that a home canner would need to learn and know how to successfully can using a boiling water bath method is included in this 15 page file. It even includes jam and jellies and some information on fermenting foods with advice about possible problems.