Just my 2c........If the block they supplied had oval cylinders ..how did they re-use the pistons?
The block should be bored sleeved or replaced. Did they reuse the old block??? After the amount of money that was paid for the motor.........actually regardless what you paid it should not have oval bores.
A normal rebuild might burn a little
oil whilst it is running in and how that happens depends on your driving. A high performance motor does not do well at traffic.....