There is no way for the Installer or any software to detect the presence of the Power Macintosh Upgrade Card through any gestalt calls or hardware detection, unless it is turned on and active during the time of the install.
You must be running a version of System 7.1.2 or System 7.5 that already has the Power Macintosh Upgrade Card software installed and active for an Easy Install to place Power Macintosh files in the target System Folder.
If the Power Macintosh Upgrade Card software is not already present to activate the card, then a Custom Install must be selected to force the associated Power Macintosh files to be installed.
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