I have seen original Fentons that have a heat riser cast to the rear section. From what I understand, the reason that the repop Fentons do not have this is so that the same castings can be used on both Chevrolet and GMC engines. Having the cast on riser would require different rear header castings due to the dimension difference between the two engines.
As far as a heat plate goes, one can be fabricated easily enough. I made mine from stainless plate, and use steel 3/8" brake line to make the tubes.
