Hi i recently acquired a 1979 GMC Sierra 15 with a 307 engine and the turbo trans it runs and drives and im planning to rebuild the engine and i was talking with a buddy kinda joking around but came up with the idea of rebuilding it with a crossplane crank instead of a flatplane crank. What i want to know is if that would be possible and if so are there existing parts that can be used or if this will be a custom crank, cam and valvetrain. Any help is appreciated, thank you.