Robert,
The method I prefer to adopt when reconditioning 2¾ bigends is, first, to check out the bigend eye of the conrod. The mating faces of the rod and cap should be truly flat, and then, with .062" spacers fitted (in lieu of the keep plates), the eye should be truly round. If not, then it may be necessary to set the rod up in the lathe and take a light skim out of the eye. Take a note of the bore size - the new bronze 'shells' will need to be this diameter or a couple of thou larger. Having turned up a bronze bush to suit the bore of the conrod and with a bore 2 thou larger than the crankpin, fit the bush into the conrod and with a sharp scriber, mark the position of the ends of the 'shell'. Cut the bush in half with a junior hacksaw, just clear of the lines and then machine up the ends so that it fits the rod and stands a couple of thou proud of the joint face. Fit the remaining half of the bush into the conrod cap and repeat the procedure. This way, the joint in the shells is in line with the joint of the conrod and cap - if you adopt the method of soldering the 2 halves to the spacers and then finish machine it, there is no guarantee that the joint will align with the end of the rod - with the result that one or both of the shells will not be clamped in by the keep plates.
With the rod and shells reassembled with new keep plates, the whole should be a free fit on the crankpin - remember, there is no pressure fed oiling on these engines, so there has to be enough clearance for oil to find it's way into the bearing. Also, with poor lubrication, heat will be generated inside the shell, which, on cooling, will curl tighter and be a permanent tight fit on the journal (as well as slack in the rod).
If the assembled conrod/bigend is too tight on the crankpin, dismantle and scrape away any high spots - do not resort to emery cloth - this will only leave small particles of grit embedded in the bronze, causing further subsequent damage to the crankpin. If in doubt, err on the side of a couple of thou slack in the bearing, rather than tight. These engines run much more happily when they are free to rev.
Regards,
Eddie.