Maybe TRT is not really what you are after.
600ng/dl and you should feel ok. Of course, its really is an individual thing....so, whatever works for you. But there are way too many men in there late 40's, 50's and 60's running around with a lower test level than that and they do just fine. Case in point: my 76 year old dad just got his blood work back and was at 450, and I gotta tell you - wish I had the energy and vitality that guy did. Anybody would.
Myself, well...i'm just never satisfied, so at the low end, I don't feel right at anything under 1000, and 250-300mg EW keeps me happy, but truth is, I could do with less. And, I feel my best at 2200-3000+.
TRT is about avoiding testosterone deficiency, which is a serious problem. The hormone is too critical to the well being of a man. Also, I don't think I know a single woman over 50 not on ERT, and I know several on it in their 40's.
Maybe you want more energy than what you have now. Maybe a stronger libido. I dunno, but what you might consider is abandoning TRT and think along the lines of a never ending cycle. Find a good source, get come cypionate or enanethate and find that magical dosage that puts you where you wanna be. After that, its a matter of getting the bloodwork done on a regular basis to make sure everything is as it should be.