You have a couple choices for exhaust manifolds, but only one choice (62-66 full size except Tbirds) if you want to keep the original style exhaust pipes without any cutting.

There are repro cast iron headers and Sanderson shorty headers that will only require minor changes to the exhaust pipes.

In 1968 Ford made a change to the exhaust port location and that can cause sealing problems mixing newer manifolds with older heads and vice versa.