If you look in the manual, you will find the ring specs listed:
http://www.lotus-europa.com/manuals/s2work/tech/index.htmCompression rings have a 2mm nominal width. Oil control, 4mm.
However, I still haven't seen a clear photo of the piston tops. Is there a raised section? Or just flat?
Once you get the new rings, check the clearance in the ring groove and the end gap in the liners. Worn ring grooves can be repaired.
Did you clean and measure your crank? If you need standard bearings then the ones you list are correct.
With the engine apart, definitely replace the main and rod bearings. The ones you ahem are very, very old.