Issue with PF30 BB on Boost frame - 2-3mm crank arm clearance
RaceFace makes cinch spindles in various lengths. I assume you have a version for 68/73mm bottom brackets. There's also a 100mm bottom bracket spindle option. It will certainly fit, but Q-factor might become too wide for your liking. Theoretically, you can also order a custom length spindle and spacers from some CNC manufacturer.