Head Bolt Question (on a BMW)

I know this is another car but I wanted to run something past you guys.
My nephew's (He's 17 but pretty smart) BMW Mini had something let loose in the lower end and put a hole in the block. He tore it apart and got another short block. He supposedly inspected the head for bent valves and put it together with a new timing change, water pump, tensioner and everything else BUT HE REUSED THE OLD HEAD BOLTS.

My Sister now wants me to come up and finish the job as he's working his summer job.

I told her that the head bolts need replace and I'd have to tear the head back off. What are your thougths? Since the were already torqued properly (torque value plus 90 degrees), should I just leave them alone and press on? Can I do a one for one swap since the head is already torqued?

Not as familiar with Minis, but some head bolts are reusable. If they are TTY, then they should be replaced.

If I owned the car, I would replace the bolts, one by one, and torque them to the right spec, without repalcing the head gasket again.

+1^^^^ but first find oit if the bolts are reusable. My bet is no as I just finished a head gasket job on a '91 BMW 850 and even that had torque to yield bolts. Pretty much all manufacturers now days use those bolts. They are much easier to consistently torque them to spec durring assembly so almost all use them.