My advice is to get started with what you have and work up.
Many of us (I for one) spend excessive time and effort with our gadgets for loading while some just load and spend lots of time practicing with the same or better results.
Let the rifle tell you what it needs. You may be surprised at how well it shoots just following basic/safe handloading practices.
As stated above, start with good components that have been successful for others.
... lapua brass, fed 210m or cci br2 primers, varget
Your best LRH bullet may be limited by your twist. So, check that first.
Here's one of MANY related threads...
There are many more specific threads here about specific tools and methods.
The HNL COAL and headspace gauges are great. But if not used correctly, they can be counter-productive. e.g. The modified case may have excessive headspace. So, you need to account for that or you won't be as close to the lands as you think because you're checking the distance from the shoulder to the lands rather than from the bolt face to the lands. Loading a dumby round to check COAL may be as good or better. But as with any tool/method, it all depends on attention to detail.
A methodical procedure for load development will be more rewarding than trying too many varied components.
Once you get started and have more specific questions, the quality of the responses will continue to improve.
Have fun and be safe.