I have some anecdotal evidence mixed with some research evidence about tamoxifen aka Nolvadex.
I was prescribed 10mg tamoxifen OD PO for gyno and took it for about 3 months. I was also taking 35mg T-cyp EOD, 0.25mg anastrozole eod, and 250units hCG eod. I weighed 197lbs at the start and benched 305 no problem without a spotter. After 3 months my training and protocol stayed roughly the same but I lost 15lbs and my bench went down to about 275. I became much leaner which was a bonus but felt like I was going backwards.
Switched to 10mg EOD for 6 weeks, still the same.
Stopped taking it altogether for 1 month and gained 10lbs and my bench went up again.
Started getting a bit of gyno and researched low dose tamoxifen. I found evidence that once-weekly dosing was much more effective in controlling breast tumor growth than placebo. The half-life of tamoxifen is about a week so plasma levels can take a couple weeks to drop.
I took 5mg tamoxifen E5D when I felt the gyno itch and some swelling and it took care of it within a week.
I now take 2.5mg E5D and so far so good.
There are some nasty risks associated with this drug and an interaction with anastrozole so less may be better than more. If you're taking tam/nolva consider trying a lower less freq dose once your gyno is controlled.