Doesn't the Lyman manual also include subsonic loads? Wholesale Sports had one on the counter a few years ago and I was flipping through it and found subsonic data, I should have bought it but passed since I was already spending more than I went in intending to spend.
Multiple sources of data is mandatory in my opinion. A couple published manuals and links to Hodgdon, Nosler, and Sierra online data is the minimum.
I've also found sites like
http://optimalchargeweight.embarqspace.com
https://www.chuckhawks.com/index2k_reloading.htm
http://www.reloadammo.com
https://www.gunhive.com/load-data/
http://www.accuracy-tech.com/list-of-articles/
There are more but those are the ones I found quickly that have data or instructions
Lots of reading to do, it's all worth it to get it right.