I did all 8 of my cables on 1976 43 DCFB about 4 years ago. I attached the old cable (the inner part with threaded section) to the new cable with 4 zip ties. I then used old cable to pull new cable thru. I do recall pulling access panel in salon as well as getting hand up into that tight space where wires and cables come down in electrical panel access closet (the main stateroom closet, space is to upper right of back of main electrical box. You need to get access where ever you can to help coax the cable around corners and/or get wires out of the way as you pull - you don't want to catch a wire and pull it out in some inaccessible space, slow and easy wins the race . For upper helm, I did take rear panel off that 4 sided teak column/wire chase to again help coax cable and move wires out of the way. Attaching new cable to old cable is key.
I got the cables from Sam's as they were good enough to provide me with original lengths of all 8 cables. I couldn't find lengths/part numbers on the original ones. If I recall, 2 of the 8 were slightly shorter (don't remember which 2, I have Cummins 903's) and I had to change route a bit to compensate in the engine room. I want to say it took about 12 hours start to finish, but this included disassembling throttle and gear controls to clean and re-lubricate. Time also includes dialing in the cable lengths and stop screws on levers.