To be on the safe side use brake Kleen CRC brand to clean up the oil
Replace the valve cover gasket, (very easy to do) while doing so remove all the plugs and make sure they are clean, if there are deposits on them use some sand paper to clean them up.
The sludge issue is a simple issue to confront, Use transmission fluid to clean the engine
Drain engine oil
Pour 4 quarts of transmission fluid (dexron III this was basic trans fluid for GM vehicles for years available at all auto parts stores) into engine allow to run for 5 mins at idle
Do not under any reason press on the gas pedal
its a good idea to replace the oil filter before you do this but not required
drain the transmission fluid
replace oil filter (I prefer mann oil filter, mahle, or Full) these can be bought off the internet
fill with synthetic engine oil (I prefer mobile 1 or Valvoline but as long as its a full synthetic its fine)
Once engine is back together and full of fluid start engine allow to idle for 5 mins, then turn the engine off, wait 2mins, then check engine oil.
If you use any oil thicker than a 5w30 oil can get held up at the top of the motor and take forever to drain down,
something like a 5w40 would be great for the engine but if the temp outside is over 70degrees its to thick, and when the temp goes up, and the engine gets warm it will flow like water.