1969 cuda engine swap

If that going into that '66 Barracuda, are you using the stock 273 exhaust manifolds? If so, have you test fit the driver's side to see if you've relieved the head casting so it will bolt down without breaking? Those smog heads need the A.I.R. holes plugged and #7 outlet machined to allow the manifold flange to sit flat. That's a rather touchy bit of machining that is best done with the engine out (actually it should be done before the head is rebuilt in case you break through into the water jacket). Also, that oil sending unit is incorrect for a '66 Barracuda. Those cars all have a gauge, not a light and that is a light sender.