There are (at least) three (3) combinations of OE flywheel, clutch (pressure plate/friction disc) and throwout bearing; are you sure you're using the right combination for compatability?
Your description makes it sound like you're not getting enough travel to push the pressure plate in far enough to disengage the driven disc. This assumes that the trans goes into gear okay with the engine not running.
There are other tests you can try, but the rear wheels need to be safely and securely raised off the ground...