Here's the 1.5" arm. The Hughes roller is 0.535". The way I see it a 0.300" roller tip would not affect the sweep distance. It would, however, effect the correct installed height of the 7/8" shaft if a 0.535" roller were replaced with a 0.300" roller on the same rocker arm. In reality, if one company used a 0.535" roller and another company used a 0.300" roller, the whole geometry of the rocker arm would be different.
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