Thanks guys. actually Darren the bottom rail coming out is only to allow access up behind the tv to compress the release clips. If it was fixed, even with the tv tilted back it would be too tight to be able to reach up behind and take it off. as far as cables and electrical those will be cut into the back once its installed.
now I just need to get the stain right, the finish on the original mantle is minwax poly with the stain mixed in in a pecan shade. it has been there for several years so of course the wood has darkened as well. Now I have this nice new freshly sanded pine top and the pecan poly finish is very very light and I will have to darken it up. I cant use one of Daves concoctions because the carcase is plywood and Im concerned with the veneer lifting. I took a close up pic and will have to play with some colors to try and match it....