These engines have extremely thin liners (only 2.0mm on the early engines, and 1.5mm on the later ones), so they really can't be bored too much, in the conventional sense. In fact Lexus states in bold letters "Never attempt to machine the cylinder because it has a thin 0.08 inch (2.00mm) liner." So about all you can do is hone the existing liners, and go maybe 0.5mm over.
The only option for serious overboring, is to bore the existing liners completely out, shrink in a new set of liners, and finish bore them. Expensive and AFAIK, hasn't been done successfully, and without leakage, yet.
The rods are easy and cheap - get a set of the Lextreme forged rods.