not to come off as a dick or anything; but these kind of questions are asked when your waay over your head;
if you want to do anything to a finished guitar, first you strip off all the clear and sealer; if you want to add a 1/4 " then yes, you have to take off that much, plus if its a les paul the top is carved, then after you howevere get the top on you have to reroute all the front cavities; the pot holes will be long gone, and then...if you choose to recarve the top, after that you can think about finishing it;
'I' would take that body, trace it onto a piece of mahogony, and put your top on that; then skoot over to the solid body section and get some finer pointers of construction;
dont get ahead of yourself; and enjoy