I would say see how you feel after 4 weeks and if you feel good, then slowly increase it, 5-6 weeks should be enough, so 20 first few days, 30 rest of the 2 weeks, see how you feel and bump it to 40 for the remaining and seeing on how things go, 50. Keep an eye on your BP and I would have a few things on hand such as aromasin/prami, just in case you develop gyno, letro being the absolute last resort, but hopefully it won't come to that.
Epi is a steroid and if you don't do the right things, yes there's a good chance of liver failure; not drinking enough water/supps, etc. If you haven't picked up nolva already, do your body a major favor and get torem or clomid; pick one, lemme know and we'll put in the doses, or you can google it. I wouldn't use a pwo on cycle, I've tried it several times and feels like I'ma vomit my heart out sometimes.
I would suggest starting off with the sarm, depending on your goals and work your way up, especially after an injury; I had to wait a bit of time and ran sarms/1andro coming back from certain injuries and after a mini pct and pre-load hit a cycle. But if your mind is already made up, least we can do is help and I would look around at a few more logs around here with epi to make sure you know what you're putting into your body and see what others, including myself, use oncycle and PCT.