OldSchool!...
Some fine suggestions to be sure! I will tell you what I do, as I have encountered this VERY THING on some drums that I have purchased/restored...
If you want to remove the "smoke smell" and clean the interior ply at the same time without removing the date stamp, try an "Enzyme" based cleaner. I use "Kinght's Spray 9" which is probably a regional product, although I can't be sure. Another readily available cleaner that is along the same lines is good old "Fantastic" or even "409". Liberally spray the entire inner circumference of the shell... let it penetrate for about 30 seconds or so... and them wipe up the "sludge" with a paper towel or cloth of some kind. The inner ply should be free of the smoke smell, and cleaned at the same time, with no damage to anything on the inside. If you have concern for the date stamp, spray around it, and wipe that particular area gingerly. I have yet to lose a date stamp with this method/products. Also...
You asked if the "sound will change" by doing any of this... and the answer is... no. The only way you would be able to modify the sound would be by FILLING IN the inner ply with a material that would make it more "reflective", such as lacquer or polyurethane. These cleaning materials completely evaporate and leave nothing behind... thus ... the wood/drum is still as WFL/Ludwig initially sold it!
Tommyp