MoPedLar mentioned that this can be faked with a socket, washers, etc.
You wouldn't need a stack of washers for the stop, just a single washer would do. Once you feel it hit the stop, you stop applying force. You make a good point - I'll see if I can find a standard washer that will serve in place of the machined stop.
Faking the pusher is a little more difficult, as it needs to be relieved to not put force on the center portion of the flexiblock. The OD of the pusher is also fairly critical; it has to be large enough to engage the OD of the flexiblock, but small enough to chase it through the mounting boss. I just measured a flexiblock and called for 0.010" less on the OD of the push piece.
Haven't purchased any new mounts. I'm re-using the original parts, and possibly the ones from the used frame.