Generally speaking, the source of most reloading data is powder manufacturers and so this is the information that dictates what powder you use. All of the big manufacturers have fantastic online reloading data and publish regularly updated reloading guides.
Ramshot powders, for example, produce a vast handloading guide both online and on paper and they include an extensive list of loads with several different combinations of bullets and powders for each calibre. A guide like this is a great place to start because as well as including all of the important data for every load, such as Cartridge Overall Length (C.O.L.), they name the specific brand and type of every bullet used so you can match them exactly if you want.
Another advantage of using the Ramshot guide is that all of their powders are still available in the UK while other brands had a lot of their powders outlawed by EU regulations. Other guides, such as those from Hodgdon and Lovex, are also great sources of information.