AJ, congrats and doing it the hard way. Wow, manual drop tables. At least you shot a lot which is a great thing.
Will throw you my two cents as I am working on a similar rig for a hunting friend of mine. He elk hunts and encounters many areas where 600 to 800yds is the norm.
First thing I recommended was a laser rangefinder ie Leica or elite 1500. You just got to know the range and it speeds up your ability to engage many many times faster. Wouldn't bother with a PALM though. A good drop chart is all you will ever need.
Personally, I believe in impact velocity and bullet construction. Ft lbs has been a pretty flaky measure for me. I have hammered a few deer with LOTs of ft lbs and they did not go down any quicker then when using lesser numbers in the right place. In fact, just the opposite (probably a fluke, several times over).
My portable LR rifle is a Savage 110 in 7RM launching 162gr Amax at 3150fps (yes, thems are toasty loads). I ALWAYS put a muzzle brake
on my LR rigs. With the present ballistics, this bullet will arrive at 800yds with more then enough velocity to open up and do good work. In fact, for LR hunting, make sure you use a lightly constructed bullet. You want the same expansion way out there. Have a second tougher bullet for up close hunting if need be.
I consider this a good min. Wind bucking is also spectacular. So I can recommend a 7STW or 7RUM to achieve the same or more velocity at sane pressures. Personally, heavy 7mm's are all you need for your intended task and recoil would be light enough to not need a brake.
My friend will have a spotter and is partial to the 300WM. I don't feel this is a large enough case. Min in a 30 would be the 300WBY and a longish barrel (28 to 30" would be just fine). With a 10 twist, should have no issue getting 200 or 220 gr bullets to 3000fps.
This equals (almost) my 7RM in wind drift and certainly will provide an increase in thumping for piece of mind. Again, this rifle will have a muzzle brake because I consider spotting my hits a necessity. For LR hunting, I will have plenty of time to put on hearing protection.
For a brake I would suggest the Micaluk AR15 brake. Just open it for your calibre. The Holland is the same style but the Mic is wider for a bit more recoil reduction. These baffle brakes work much better then the KDF style single expansion chamber brakes. Forget anything that vents forward. I want all the recoil reduction I can get.
As to the rest of the rifle, really up to you. I prefer repeaters as you just never know if you will have time to fiddle with a single shot. With long magnum actions, there really isn't any problem getting a repeater. The issue of better accuracy with a solid action? Certainly, haven't found any accuracy problems with my repeaters (all shoot 1/2 MOA or better at LR).
so if going factory, the Savage is a great place to start. The 110 action will easily digest any of the long magnum monsters and is an easy action to work with. You can get a heavy barreled 26" model in 300WM. Run a 300Wby reamer in, change the mag box and you are good to go. These factory rifles can shoot very well.
A Rem 700 in a 300RUM, WBY or 338 RUM would also work. However, I would not suggest the 338 as wind drift is not as good and that is more important then a few extra ftlbs.
Top any of these with quality optics and start practising. you have the experience of working up a rifle and load. I know you will be successful.
I have a 300RUM cannon that when ballasted weighs in at a lofty 35lbs. When shooting 240gr MK, it will recoil 3" which is a lot for a shoulder to handle. A very big slow push but jarring enough to be uncomfortable. A simple but large single port was milled into the barrel. Recoil is now 1" and feels like a 22/250. So if you want to shoot 240 to 300gr bullets at 2800 to 3000fps in a 'light' rifle without a brake, be prepared for very serious recoil. Not my idea of fun.
PS there are at least two more posts on this page with thoughts on the same thing. You can read other perspectives on the issue.