Hey brother, I think you have some things backward here. So lets go through this one step at a time. First you want to run test through your whole cycle. It takes test cyp about 3-4 wks to really kick in, so running it for 3 wks will do nothing to help you through the cycle. Next, you do not want to use t3 in PCT and the other meds will not be great either.
Since you have not run a cycle in 10 years, you are pretty much brand new to gear again. A much easier to do cycle with low side effects and great response could look like this :
Test Cyp 500mg EW split into 2 shots
adex .5mg to 1mg EOD, more if needed
Geneza Mast 200, 400mg EW, split into 2 shots
Winstrol 40mg oral ED
Then PCT would start 2 wks after your last shots. You can continue to take the adex into PCT and at this point, start Clomid 100mg ED for 7 days, then 21 days at 50mg. Since you are 51, you might have a harder time recovering than when you were younger. I would suggest that you get labs done before you start to see where your test levels are. From there, you will better understand what to expect to return to after the cycle. If you qualify for HRT, and want to use it, you would simply return to your HRT dose of test after the cycle, no need for PCT