my experience tells me take everything off the head before removing it. The intake manifold cannot be attached to the head, anymore than the exhaust manifold or the timing chain....Yes, the intake manifold can remain intact in the engine bay and be reattached, it's the preferred way actually.

Just thinking about how many I've done....Peugeot 504D, BMW 2002, Fiat 131, Honda Civic, SAAB 900S Turbo, VW Rabbit....in all cases it worked but you had to take everything off first and basically do it right......