Re: evenruide 6 hp shifting leaver.
any idea where i might be able to get a detailed guide on how to take the power head off
Here is a link with a lot of good information about your motor.
Johnson
You will need to remove the power head to get the shift lever. Take pictures as you go so you can replace things if you forget. Use plenty of cheap zip lock bags to separate and organize your parts, so they don't get lost and to organize what go with what.
Here is a youtube link that will show you how to remove a powerhead from a late 50's to early 1960's 5.5hp Evinrude Johnson. It is very similar except for a few things, but it will give you a very good idea on how to do it. The you tube video states dropping the lower unit, but for the 5.5hp motor removing the powerhead was required to drop the lower unit, but not with your motor. I would like you note the carbon washer/seal that is described in the video is important to change in your motor and the only way to get to it is removing the powerhead. That seal keeps water out of the powerhead and is not often changed or inspected. You have old good motor, so the seal should be replaced and inspected.
*** remember to change powerhead's base gasket as well.
YOUTUBE LINK
Dropping the Lower Unit on mid 50's 5.5 and 7.5 Johnsons and Evinrudes - YouTube
Here is a digital diagram for your motor.
1969 Evinrude 6902M 6 hp Outboard Motor Parts
Good luck