if you can not locate it you can pull the sump pan to get at the lower end you then pull the 8 main bearing ladder bolts and drop the ladder with the windage tray/oil baffle and you can get into the whole lower end. Oh and the only time I reseal liners is when I pull them. I have changer the pistons and rods without pulling the liners. And I have done it the Triumph manuals way. Personally I would just order new rod bolts and change the pistons from the bottom leaving the liners. I have swapped heads, cams, pistons, and rods without pulling the motor or the liners.
can I ask which cylinder and do you have the clutch cover off the front of the engine?