With the fairly recent development of nickel-alloy MIG welding wire suitable for use on cast iron, it's possible to do a good job of building a real split manifold instead of using the overseas-made repops that don't fit. Then the original heat riser can be used instead of some Mickey Mouse aftermarket heat plate. Even a welder with mediocre skills can do an acceptable job of splitting the manifold with a MIG and a little time.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!