In your signature, it says "all original". I assume that means original radiator. I would think that instead of crutching it with wonder products, you would want to remove it and have it reconditioned at a radiator shop. Also, check the lower radiator hose for sucking flat at higher engine speeds. If it doesn't have a spiral wire in it, replace it or find a wire that will fit. Replace any sheet metal panels that you may have removed. Maybe the air is going around the radiator instead of through it.