Well, the simple fact of the matter is that we cannot sit here at the computer and tell you what your rifle is going to like.
Your rifle will tell you what it wants, and each rifle seems to be a law unto itself.
My advise is to start with a load of 1 grain per caliber, in your case 45 grains, and shoot a three shot group off a bench. I like to do this at 25 yards, as that alleviates problems like wind drift and vision problems, etc. Mark your target with load data. Set a fresh target.
Increase your charge by 5 grains and repeat the process. Do not change any of the other variables like patch thickness, rb diameter, lube, etc.
Increase your charge by 5 grains and repeat the process.
As you go through this process, you will notice the grouping should get progressively tighter. At some point, you will notice that the group will start to open up a bit. You have just found your maximum accurate load. If it is still not completely satisfactory, you can then play with fine tuning the load. Change only one thing at a time. And, as long as you are hitting on the paper, don't worry about changing sight settings, do that after you have your load figured out.
As regards you previous question, I don't think it makes a lot of difference whether you use Ffg or Fffg in your .45, as long as you tailor your load for the powder granulation. Personally, I am a Ffg user, and I put it in everything from my .45 to the .72, including my Ruger Old Army. I usually use Fg in the big guns, but have experimented with Ffg in the 8 bore. Made a 100 fps difference.