If indeed the oil is getting passed the piston then a set of rings and a bore hone may fix the issue, however you will likely find that the piston oil glands are damaged, so a set of pistons and a rebore may be required.
When you are there ,best to fit new bearings to the crankshaft.
The above is just to address the oil problem, and is the cheapest way to fix your issue, however if you wish to go forged and then remap to increase the power then that is a completely different ball game and the extent of the build will depend on how deep your pockets are.
If the diagnoses is correct, the next stage would be to remove and tear down the engine for inspection and quotation.
What ECU are you running?
What are your current power and torque numbers?