Radiator

Pre-77 4-cylinder: The two seals - rubber from the diaphragm to the bonnet up to the start of the 1977 model year, and foam from the start of Mk2 production again to the start of the 1977 model year between the radiator and the diaphragm. Note the overflow tube exiting forwards and going down the front of the radiator:

For completeness the bonnet seals are shown here.

Packing strips: There should be packing strips AHH6320 between the radiator and its mounting panel, to space it forwards slightly. Two per side up to chassis No. 146506 in April 1968, one per side thereafter until the radiator moved to the forward position with electric fan(s). Clausager describes the April 68 change as 'Radiator modified with repositioned mounting plates', but this doesn't coincide with either of the radiator changes listed in the Parts Catalogue i.e. at Chassis No. 138401 and 386601. (Motaclan/Leacy)

Overflow:

Bee (1973) has the overflow port on the filler neck angled forwards and the tube going down the front edge with two clips:

With one packing strip each side there is a 3/16" to 1/4" gap from the radiator to the rear edge of the shroud:

This from Clausager every other picture I have seen has the port angled backwards and the tube going behind the radiator. Note this does not have the foam seal:

Cores: Mk2 pre-77 tube pattern - does this make it a 2-row or a 4-row?

2" from the top of the tubes to the lowest part of the filler neck (it is angled forwards slightly), coolant level should be 1" below when hot, so only about 1/2" above the tubes when cold or it is likely to push some out when running, and you will be continually topping-up ....

V8 and what is supposed to be an uprated core with 25% more tube area. A much smaller fill port although the tubes themselves are of the same or very similar size. This is the middle row, the other two have been simulated: