which spark plugs for 1990 300ce

hi, i have a 300ce 1990 . the exisiting plug are HR7DC+5 but i need to replace them.
the 1990manual (22 years old now!!) says use bosch H8 plugs..
i have been reading the forums and i believe that the H8 may be superseded by the HR7.
what do you recommend? thanks