Changing when? while looking for the problem or during the failed trip??

I have filters at the tanks and forward the fuel pump. We have cut them open periodically, NOTHING has ever show up on the filter material ever.

When the fuel pump rusted internally we had rust on the carborator filter and inside the carborator body. The carborator had to be replaced at that point.

I have never had anything show up in the fuel line filters.

""" Just brainstorming here...... Since the problem(s) all started after dropping the tanks, I'd check that work first. Any chance the hoses were kinked or misrouted when reinstalling tanks? Even the best repair shops have the occasional Newbie, or Friday afternoon syndrome. The fuel system is fairly simple (compared with trucks or fuel injected cars).
Also, "cleaning the tanks" may have dislodged crud that landed elsewhere, like the mechanical fuel pump (another relatively cheap item to swap out). I recall one time I was running the parts department at a foreign car shop. A mechanic was replacing all the aged fuel hoses on a VW Type III, and I had given him a 20 meter or so box of hose to cut from. After a time I heard swearing from the shop, and the mechanic threw a piece of hose and some dead insects on my counter. The bugs had crawled into the hose in Germany and stayed to clog things up in Hadley, Massachusetts. Weird things happen!

Sometimes when I didn't know the history of a vehicle, I'd try setting everything back to "stock" conditions and work from there, but you have to do it in order, or in your case, maybe all at once (tank to carb.) And as someone mentioned, it could be something else, like HEI module, cap, or rotor.

I hope when the (justifiable) frustration ebbs, you'll be able to give it a slow, methodical try again. We're all here to help if we can. """

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=== Yes the problem was born from the Tanks being dropped and the hoses changed out.
Those tanks were sent out and checked/cleaned and then re-installed. I didn't see them when installing back in the frame so no idea other than the problems with fuel as far as hoses go.

=== crud landing in the mechanical fuel pump would be tough, the fuel line has always had multiple fuel filters, no crud ever showed up on the filter material.
I have had the mech fuel pump changed out 4 times now.

=== After we took the tanks and hoses out of the picture, we began getting the power back.
This shop, after the power loss problem showed its ugly head, did not go after the tanks and hoses, they began changing out the carb. They said my
carb was not "spraying fuel" into the throat of the carb, it was dribbleing fuel. They went through 3 rebuilt carbs and non made any difference
in the power loss. The final carb came from a used GMC motorhome. No cure and when My mechanic checked it, it was dribbling fuel down the carb
throat too. We have been through 4 carbs, including the one I now have.
They also changed my coil over to electronic and changed out the distributor with a used one. ???? I am a new GMC owner (at the time) and needed
to get home so what am I going to say? and history shows, none of that corrected the power loss problem.