FG-60R3 About the cracked head.....
Honestly...... That isn't a big deal...... Horizon will fix it..... I hope the piston isn't seized..... I am guessing the cyl had a bad casting....
If this is what it was.... If you have a casting issue or some other bad from factory issue.... The good news is.....IT WILL BREAK RIGHT AWAY.....
Once you get over that hump.... they are going to be solid...... that is why a lot of racers hate to start changing out parts on full size engines...for the "SAKE OF ROUTINE" checks.