Is changing the valve cover seals on a 1974 450 SL a difficult job?

I have only done one other valve cover seal job myself....it was on my 1966 Mustang and it was easy.

Last (probably dumb) question.....do I need to drain the oil first?
On the Mustang I did not have to....these valve covers look deeper though.....

Thanks for your help!

Mike

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1974 450SL 99K miles
1996 C220 142K miles
MBCA Concours Judge
Western Reserve Section