I'm going down the same road, my first time tuning a rifle. Smarter people than me can come in and correct me but here are my thoughts. Also go to my thread in the Silencer Forum (in the Armory), look for 'Adjustable Gas Block, Buffer, and Spring'
To get the 3:00 - 4:00 ejection pattern the bolt speed and unlocking need to slow down. Several different ways to do this, some better, some easier.
Do you like to work on your guns? Maybe have or will get a few tools? What about your front sight? Do you want the rifle to cycle reliably with and without your silencer, will you change the settings or set and forget
Best approach is an adjustable gas block (AGB), the most difficult, but not hard at all, $40 - $300. Rifle speed is very easily adjustable, heaviest and expensive. Superlative Arms, as well as having a gas reduction ability, it can also bleed off gas through a second port, mid priced. Then there are a huge number of AGB between $50 and $150, take your pick. SLR gets a lot of love here, semi-inexpensive, light, popular.
BZT Gas Tube, a smaller diameter hole in the gas tube to reduce the gas flow, go to their site, answer their questions, and they will get you a more appropriate size. Is it 'the perfect' size, don't know but it will certainly be better. Likely to run both w/ and w/o your cans, all you need to do is punch out a roll pin to replace, easy.
Adjustable gas key, similar to the AGB where you are throttling the gas, but you are doing it at the bolt carrier. Gas is still coming down the tube but you are choking it down prior to entering the bolt, likely to produce more 'port pop' as the gas is released out the ejection port. How much louder, once again, I don't know. Tests have been run, but logic states the gas has to go somewhere (some of it goes out the front of the upper). About the came cost as a AGB, maybe not the absolute best solution but pretty easy and still adjustable.
From my understanding, buffers and springs are more for tuning recoil, but will also effect ejection pattern by keeping the bolt closed longer. Once moving though, more buffer weight = more momentum = more perceived recoil, unless you can keep it from slamming into the rear of the buffer tube, perhaps with a heavier spring; most seem to prefer a +15% spring rate (Giselle, Sprinco). Giselle comes with a proprietary buffer. Griffin makes a suppresser based buffer (Suppressor Optimized Buffer which I'll likely be picking up), Kynshot hydraulic buffer is also popular, and others I don't know about. Very easy, but you'll have to find the right combo that'll give you the ejection you are looking for and the recoil upgrade.
I'm sure I missed a few things, but start researching and let us know what you decide.
Me? I am going to try the AGB, probably the SLR, get the Griffin SOB (maybe Kynshot), and possibly a flatwire spring or Sprinco something in +15% rate and tune from there for ejection and recoil. You can step up to H1, 2, or 3 and, the gun will still run reliably from what I hear, but you still have to test for last round bolt hold open
Vltor A5 kit is highly respected but I don't know a lot about it though. Lots to learn and unpack, good luck!