52 feet was added forward of crews mess. The hull was cut forward of the water tight bulkhead and the forward section was dragged forward on rails. This included the torpedo room and forward berthing. The projects plug was inserted and welded up to the aft section then the torpedo room was dragged back and welded up.
you will see several reference ( correct and incorrect ) to the complete total length on the internet. in several side shots after the conversion you can see were the curvature changes were the project section was inserted. some equipment in the torpedo room was installed making a couple torpedo tubes useless, they used them for cold storage during long missions
the difference between ssn571 and ssn575 was mostly forward of reactor compartment. the 575 had a conning tower were the 571 did not. the attack center and wardroom area were different but the torpedo rooms were pretty close.
the aurora ssn575 model is just a ssn571 model relabeled.
the 52 " project section was a constant diameter part. if you were to take a cross section of the hull at the crews mess bulkhead and make it 52 ft in length it would not change in size or shape. this was so it could weld up to the torpedo room.
NOTE !!!!! this is copied from several sources on the net. I have not released any info that is not already public knowledge. ( covering my ass )
here is a photo of the section being installed http://i0.wp.com/www.defensemedianetwork.com/wp-content/uploads/2014/01/USS-Seawolf4.jpg