I did the exact same thing with the 78mm rods. When I inquired, I was advised that I could have used the 30 mm rods for the tail push rod. Too late by then as I had also glued them in as I was following the manual. See if anyone on here has a couple extra laying around, they may be able to send them to you. If not, there were some for sale from Experience RC and it's around 5 bucks to get a replacement set. That was actually the only problem I had with the whole build.
As far as the sizer I'm sure someone else will be able to chime in with better info. I don't remember what I used exactly but I thought it was the biggest one. Regardless be careful, there seems to be a fine line between making them the right size and then over doing it. I would highly recommend you order an extra set of links and practice with a couple.
Regards,
Brandon Bartolomucci
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