I cruise at 300 mg a week but im 39 and know thats on borrowed time. Id be a little leary doing this at 50 I would make sure you kept estrogen in check. I watch my bw closely my lipids run a tad higher than normal and I need to dump blood frequently due to high rbc. Will 300 kill you probably not you just have to be careful and watch your numbers
I dont plan on running 300 for long term as I age I will eventually slow it down some