There is no diference in bbl spacing & wts possible to achieve between Conventional (V lump), dovetail lump, or chopper lump. The dovetail chopper lump or through lump will almost always add width to the bbls while the shoe lump will add heighth. All the Lefevers I have examined used the conventional V-lump, which as they were top bolted had no reason to add the dovetail to lower lump. Have never heard of one of these failing in the jointing either. Some very early breech loading doubles were even jointed using soft solder, the brazing would be a great step forward I would think.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra