First off.. the one on the left hand head... you have it on the end of the metal cross over pipe... the expansion tank should be connected there...
looks like the hoses from the expansion tank are connected incorrectly too..
the ones on the right of the engine bay... there should be some hoses that go ove the gearbox bellhousing and connect to the larger pipes.. the smaller one (should actually be 2

) are the heater supply and return that go onto one end of the metal crossover pipe and the hose connection on the right head (same connection as the left head where you havent got the hose connected)
Dare i suggest... that whoever took the engine out should have taken a little more care and labeled the connections...!!!
Or here is a thought... buy a haynes manual and have a look in it!!!
Having taken a second look at the engine... there are "bodged" hoses hanging over the back of the carb... (they dont look "factory") and I reckon you should look at what you took out...maybe the pipes you need are still on the old engine??
Failing that, I think to do it right you need to see a comparable van and get the correct parts, several breakers on here will have them...
Other wise you will have a crappy system that will kill the engine (again??)
Third look..... Whats that coolant hose (19mm ish) doing running round on the right hand side of the engine??? thats not right... no hoses that side.... they all come and go from the left (apart from the 19mm heater hoses)...
Must be a member near to help out... maybe Clive?