Your requirements seem to be flawed. A 32-bit package as indicated by the template summary substring of Intel will normally run on both 32-bit and 64-bit systems. (See Template Summary Property for some details.) To prevent a 32-bit package from installing on a 64-bit system you would need to add blocking logic--such as a launch condition or a type 19 "error" custom action--to exit the install whenever VersionNT64 is defined.
