It doesn't matter if you have full coverage or not because it was the other guy's fault. You will be able to recover the cost of the car AND any major work/repair (your swap) you have done recently. Don't let them get away with not reimbursing you for the cost of the swap. For all they know you got a new engine because yours was bad, so make sure they continue to believe that. I hope you have all your reciepts as well.