It is possible to replace every single thing on the truck that has any amount of rust at all. I evaluated the overall condition of my hard lines based on what I see from the outside, which of course is not possible. Boy am I full of boloney. :-) In the end, I decided if they were not leaking and flushing them out resulted in clear gas arriving at the other end, that would be good enough. Good enough may not be compatible with your personality, and that's OK. I did end up bending my own replacement fuel pump to carburetor fuel line because the previous owner had cut the line and added rubber hose and I didn't want any rubber hose on the pressure side of the fuel pump. A pre-bent fuel line is not available for my truck, which has the
1969 insanity air conditioner bracket. The other hard lines are original. I had a metal canister type of inline filter in the short rubber hose section right where it goes into the fuel pump, but a few months ago I removed it. I've now driven the truck for a couple years and the lines are still going strong and the built-in carburetor filter is working fine. When I pulled the old filter after going over a year, other than looking wet and being just slightly darker than the new filter I was putting in, and also not finding particles, I decided those hard lines must be just fine. I'm not saying it is overboard to replace the hard lines, there just had to be a limit to the budget
for me (both dollar and time budgets). I believe driving the truck often, going through at least a tank of gas a month, is beneficial to the fuel system. If you plan to drive yours somewhat rarely, then all new fuel system components and completely rust free system is what I would suggest. That's my 2 cents.