considering that you get a nice feeling from 25mg of oxy, and that you're going to swallow the pill, i'd suggest taking maybe 60mg of morphine
. this is because the oral bioavailability of morphine is ~25, whereas oxy is ~80 (sources vary some. you can do a google search to get some ideas).
to be honest, many people (myself included) seem to be disappointed when taking morphine orally, especially when compared to oxycodone
. soooo... my 60mg morphine suggestion may be slightly on the light side. but with opiates
, it's always best to error on the light side.