They look really good so far !! I like the granite color/texture/look
Just a little more info and advice....
I see heat being your biggest enemy here. Any 1 KT-88 runs between 160-180 degrees while our amps are at rest.
The chassis' get hot, because of the tube pins and tube sockets.
The majority of the heat is transferred via the tube pins and bottom metal bands, down through the socket clips to the internal section of the chassis where the wires and parts are soldered.
There is of course also the ambient heat created by the glass portion and the bottom band of each tube.
Carver designed the chassis' to keep themselves cool via convection. The base plates of the amps have ALLOT of large holes in them, as does the top deck of the tube chassis.
The isolation feet, keep the amp chassis about 1.5" off of the granite bases, allowing enough cooler air to be sucked up from the bottom of the amps, as it passes through the chassis, and up past the tubes.
From the looks of this photo you posted......
I don't think you have anywhere near enough top ventilation slots.
The Silver-6's - 7's and 9's, all have 4 slots all the way around each tube, to allow enough air movement.
You say you plan on using KT-120's which may even require more heat dissipation than the KT-88's. The KT-120s are about 25% larger, and also require about 33% more current than the KT-88s. From what I recall, you may also need a larger transformer, than the ones Bob uses in his current amps (you really better check with him on this one!!)
I seem to recall talking to him about the KT-120s a few months back, and the amperage draw was an issue that he would have to make modifications to the transformers if he were to go over to the KT-120s. That's the reason he hasn't put them in any of his amps yet. He didn't want the re-design the transformers (yet)
I hope this info and advice helps.