Or you could try electrolysis. Either way you are probably going to lose some of the coins surface. they don't have much value in the state they are in right now anyway. Nice finds though!
try a soft bristle brush and soapy water, then a brass bristle brush, then an sos pad. Start soft and go harsher. The only value at this point is personal. You may regret over-cleaning as I do on a few of my coins.
As little as possible until you get results you like... I usually do 10-15 minutes at a time... use a toothpick to work off crud between soaks. Keep in mind, the coin will get darker with hydrogen peroxide.