Well... The .45ACP case has enough space for approximately 12grs of powder. So therefore youre fine! I didnt read what youre using for powder, but I use bullseye and my load is 5grs and im completely fine with regard to space.
I say before anything, make a dunny round that chambers perfectly. What I mean by that is no primer or powder just prohectile. Then slowly work down the seating by a couple thousanths each tims and then check it in you barrel. Continue that process until you find the length that works in your gun. Then, lock everything down and save that round for future reference.
After that, then make live test rounds, 20 or so to shoot at the range and see what works best for you. Id say 4 different loads of 5 rounds each. So, take the max load and bump it down by 10 percent, make 5rds. Then make 5 more rounds at 7.5 percent less than max. Then 5 more at 5 percent less than max and finally 5 more at 2.5 percent less than max load. And if you really want to, although i never have, you can load 5 at max. I dont think those are necessary because I believe you will find the right load for that oal with those 4 loads.
It seems like a boring pain in the butt, but safety first always. Plus, after you go through that grunt work, you wont have to do it again. Youll have a load that works and you like alot.
Good Luck And Enjoy!!