Vapor locking is more common in older vehicles now than 40 years ago because unleaded is more prone to vapor lock than the old leaded gas. I have a couple of c stores that have been in the family 45 years. We had to get rid of the suction dispensers and put in submerged pumps when unleaded came out in 1975. I would not put a filter between the pump and the tank. A restriction would cause the pump to break vacuum like holding your hand over a vacuum cleaner. It was very common in the 50's to wrap insulation on the fuel line between the pump and the carb. It was also common to put a bunch of wooden clothes pins on the line to dissipate heat. When 10% alcohol was tried in Texas in the 70's, one of the downsides was vapor locking. There is no problem because EFI requires an electric pump. I would stay away from the alcohol blends and probably rebuild the fuel pump.