Those filters are not high quality, get yourself a metal wix (Im sad wix is selling that kind..)
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This product people have said is decent when using both SBC and electric pump, as it will allow flow-through when off. which means you could have it on a toggle at the very least to check the theory about vapor lock concerns.All fuel hose clamps should be replaced with fuel injection clamps if you have cheap worm ones them up by the fuel pump, air can sneak by and then throw wrench into your issue.
as to the question of where to place an electric frame pump, if you had one tank I would say below the level of fuel if all possibly and a model without a check valve as close to the tank.
If you have 2 tanks, a check valve pump can be placed further away and below fuel level if possible, but im not sure how it would interact with tank switching valve. I believe ford in the late 80s used the same one as the late 80s GM, but they had their pump
before but I could be mistaken