07 S60R BW 7163 EFR Forged Engine Burning Oil | SwedeSpeed

Hello i have bought an R from a member on here. I flew to Michigan from Georgia to purchase it for 20k and drove it back down to Valdosta, GA. The car is built with darton sleeves and forged pistons. the build on my signature. While driving down on the 18 hour drive I received a low oil fill oil message where i found the engine to be down on the hashmark. It also smokes on hard acceleration and smokes badly on cold start. Upon finding this out when back at home I talked to the seller and he agreed to help me but i did say that i would do a chargeback on 9000$ of the 20000$ that i paid. He has since stopped replying to my messages for support. The car is burning roughly 1 quart per 400 miles of highway driving. Ive been looking through his records and He built this engine in 2017. It says he replaced the radiator a few thousand miles ago indicating he might have overheated it? I have replaced the pcv with no success and the pcv test barely passes with puffs of smoke coming from dipstick indicating high blowby. My theory is that the piston rings or walls are worn some way or another.

Compression test yielded 110-120 across all cylinders
Oil are on top of pistons 2-5 with one being clean. Intercooler piping is clean of oil. Intake valves are clean of oil. Andy rebuilt the head a year ago looking to solve a smoking issue. He also fixed a hose on the pcv claiming to have fixed it last year. Clearly this is not the case.
During my conversation with the seller, he said its normal for a built engine to be burning oil. I agree to a degree but the consumptions is quite bad to foul the o2 sensor in 5000 mi

The other possibility is the turbo oil drain line is not positioned perfectly at a downward angle enough so oil is pressuring and pools out the exhaust turbine side. But this doesnt make sense because the owner looks to have been diagnosing the smoking issue. Hes rebuilt the head/valve stems/seals. So likely this issue is not a product of the turbo.

So here i am. I plan to use the 9000 i charged back to build an engine. He is probably disputing it and planning to keep the entire 20k. What do you guys suggest i do? Ive never built an engine before. I have vida. Is it possible for a person with little to no experience to do this? I want to be honest and forward with you guys I am so sad 😞 its turned out this way. Ive owned an 04 S60R with cracked cylinder liners, blown angle gear, burnt clutch and this is turning out to be just as much of a nightmare as that one. But i love these cars and im not giving up! I want to see this car run well! Please help me restore this car to its former glory!

About building the engine i dont understand “bore” for forged pistons theres 83-84.5mm and other sizes ive seen for the forged pistons sold on Viva performance site. the seller said he used low compression pistons but i dont know what bore pistons he purchased. I want to try to make the same engine. What do you guys recommend? Who should i go with to machine the engine?

update: Did the oil restrictor and it seems to have helped smoking but it still smokes. So its pointing to not having enough of a downward angle on the turbo.