These are not mutually exclusive. I assume you mean the Heat Crossover under the carb, is blocked,and that the choke linkage has been removed or otherwise disabled.
The heat riser is a valve in the factory exhaust manifold.
So what have you installed under this TQ? The 340 from the 72Demon? or is the carb off a 72 Demon 340? Or is it a Hemi? Is it a 3.31 stroke ? or other? Does it even matter? At this exact moment;no. But in a few more questions it may be useful information.