Why spend $9.99 for $0.99 worth of common hardware?
Plugging up the heat holes in the intake manifold gasket could be expected to cause warm-up drivability problems. This assumes original stock components are in use.
Buick issued a service bulletin in '55 (attached) for complaints of rough idle, bucking, or missing. The cause was found to be excess flashing left in the cylinder head exhaust crossover passage. The excess flashing blocked off exhaust gas flow same as the bolts would.
Gaskets on cars w/automatic used 1/2" heat holes; synchromesh had 5/8" holes.
It seems the classic way to address vapor lock problems was to concentrate on improving insulation between the carb base and manifold via gaskets or spacers. Claims of added horsepower are not believable. Where is research data to support 18 HP extra?
What has been, can be again. (Bob Wills, 1942)