damn, winny300? never heard of it and based on what i know of winny i doubt it is really 300mg/ml. if it is micronized winny in either water or oil, it would be so hard to keep it dissolved in solution that the really high benzyl alcohol content will cause a ton of injection site pain and not worth it, and if its not micronized winny, you would need a friggin cannon as a needle to push that much winny through. even a 22g needle would more than likely get clogged if it is at that high a dosing.
highest dosed winny i have ever seen was 100mg/ml and it came in either oil or water and hurt like a bitch when injected.
if you have just completed a cycle then i would not start the winny. save it for your next cutting cycle and plan on including some test & maybe eq with it. you would be better off running your pct therapy post cycle and possibly running some clen with the pct.