The TX will work in most all 72 MHZ TX...the RX crystal will not work in the mini Rx....it looks like a channel 30? So you could just order a mini 30 to match the 30 TX....when you order the Rx.
Just replace the crystal that comes with the new TX. You can also find used 72 MHZ FMs on here...I see them for sale alot.
Either way, you can later order the the Rx crystal that comes with the TX you buy. That way you'll have two freqs to use. I have never had any issues with Corona RX;s good range and tough.