Greetings, Removed the old vinyl siding over top of old cedar panel siding to reveal that original part of my house has drop lap siding nailed directly to the studs - no sheathing. The addition parts have sheathing. I am installing new drop lap wood siding. I don't like the idea of installing the new siding on top of the old since it is not "flat" - each board has a scallop in it. But if that is "ok" then I'm ok with it. Do I need to remove the existing drop lap (most of it is in decent shape) and put up sheathing that matchs that on the additions, or can I cover it all with 5/8" sheathing and then reside. Thanks!