Tank you very much: advice please

Not leaking doesn't necessarily mean a clean interior of the tank. Only a visual inspection (remove and eyeball it, or an inspection camera through the filler or sending unit holes).
Personally, I would reuse the original if it is structurally sound; and I'd especially reuse the original pickup/sender if it is in good shape, or have it rebuilt. Aftermarket senders are generally not well matched to Mopar tank requirements- they function, but accuracy suffers. And save/reuse your original lock ring, most aftermarket ones are too thin and don't seal well.
Moral of the story: use the original equipment when you can.