170 to 225 swap (advice needed)

Could I reuse the oil pan from the 170?

Yes, pans are the same, but if the 225 is a 66 engine the pan will be the same. Tip if both oil pans are the same save the pan and oil pump pickup tube the tube is not available new, save both of them for resale. Also check the flywheel fit on the crank, the crank hub changed in 68 and you never know what happen to the engine in the past.