Yeah, my 57Trim from DM lasted about 500 km. Was pumping a litre of oil per 100 km.. but no word from DM about what the issue was. You do have a 9 month warranty on Driftmotion's turbos...
However, I don't know if its the turbo. Depends on how your oil is burning.
If its after a good turbo pull, that may be caused by running a tad rich and just washing the oil through the system. Hard to control that without a standalone as the car likes running pig rich for safety.
If its on any kind of decel, it could be simply blowby because you stated (I believe) that you rebuilt the top end, but not the bottom end. A rebuilt head with redone valves on top of an old build usually raises the compression and puts more stress on the piston rings (simply because now the engine hasn't worn together... the head is tight.. the block is loose). Been known to happen although couldn't verify if that's your issue.
Valve stem leaks only burn oil at start for 10-30 seconds. Unless they are REALLY bad (like mine were... not installed correctly, floating on the valve stems, disintegrating).
Watch your engine and see how much oil you are using and in what timeframe (distance). That's also a good indicator.
