The problem with using LS main bearings inside the original bearing shells is that the rear main bearing on the stovebolt engine appears to be too big to position the LS bearing accurately after the line bore job. Using small block 400 main bearings would seem to solve that problem, as they have a slightly larger OD. Either way, the stovebolt crankshaft is reground to the same size, front to rear, to fit the new bearings. Slots for the locator tabs are filed into the old bearings, or added with a Dremel tool. The only thing a tab actually does is locate the bearing correctly front to rear- - - -the "crush" built into the bearing diameter is what prevents spinning. I also like to attach the stovebolt main bearing shells to the block and main cap with flat head brass machine screws and LocTite, to make sure they don't get dislodged while fitting the new main bearings. Do that before the line bore/hone job.
I've been using a different full circle rear seal, one that's the right size to fit the stovebolt seal surface, (3.875" OD) so no alteration of the crankshaft is required. That seal is a Timken #417210 or the equivalent size in National, BCA, etc. The dimensions are 3 7/8" ID and 4 3/4" OD, 3/8" thick. If the crankshaft seal surface is worn or pitted, a SKF#99387 "speedy sleeve" is used to give a durable stainless steel surface for the seal lip to ride on. The lip seal can handle a +/- .015" diameter difference and still seal effectively. I bore the back of the block with an adapter plate I made to mount my Van Norman cylinder boring bar to the back of the engine block, but the same thing can be done in a Bridgeport mill with a long, tedious setup procedure. My fixture bolts onto the block in about 15 minutes.
Jerry
