Hi Mark,
I recently replaced both the compressor and evaporator on hull 164. I had a conduit that ran the whole way that was even straight. I just tied a line to the old tubing and used that to carefully pull the new tubes thru.
There is probably a big lump of sealing putty in the fridge compartment where the tubing enters. It comes out easy and you should see the forward end of the conduit. You will need a helper to feed and straighten the new tubing as you pull the line attached. It was surprisingly easy, just be careful not to kink anything. I went with the original AB parts as they seemed to work well for the first twenty years and I was sure they would fit.
Jeff