ok, after reading all the dryer stuff, not see the one ? i am wondering to make that idea even safe. Gas, or Electric dryer? gonna need a good damper for your grow room if you ever wanna do laundry when lights are off.
where is that hallway in comparison to the room? use a flange and run it into it. is your chimney close to the grow? can port out of it easily . don't wanna cut threw the block, remove ur door and take 10" off it, fame the top in and add OSB with 8" hole to port out. Above that block should be damn near 8 -10" of floor joist u can go thru, like a past post said go to rectangular duct. other options then dryer vent, what u do laundry 24/7? cool air + hot humid air make steam. but in the end i think u gonna need to supplement ur CO2 in the basement, those gonna be big plants i would think with 2k light, they gonna eat up a none replenish CO2 supply fast.