Honestly, I do not believe the hype around T4 and GH. Yes, people will say there is a synergy between the 2. However, those people are generally people who have never taken T4. I just don't see the point in taking T4. If you want to take any thyroid hormone, take T3, which is the active thyroid hormone. T4 requires a conversion to happen in the body. This happens in the tissue. Now, there are some other factors that affect conversion. Too much or too little cortisol, estrogen imbalance, adrenaline, testosterone, etc. I would at least say that 80% of the time, some of the T4 doesn't get converted, which then becomes RT3 (Reverse T3). That will actually make a person feel hypothyroid and shittier. So, again, if you are going to run some form of thyroid hormone, run the T3 with it. Have there been guys who have been successful while running T4 only? Maybe, but T3 is just that much better of the hormone because it is active already and no conversion is needed. Personally, I wouldn't take any thyroid stuff unless you need it. So if your thyroid is fine, then GH should be enough without the need for T3/T4. Good luck.
As for T3 doses, I would do the following:
Start off with around 12.5mcg per day. Then every 3-4 days add anywhere from 6.25mcg to 12.5 mcg. Some ramp up too fast and their adrenals get completely stressed and make them feel really hyperthyroid. That has been my experience. I wouldn't go above 100mcg of T3. Totally unnecessary to go over 100mcg and not the safest.