I am updating with pics of the fitment, which has finally been performed this month. Because it is about twice as thick as the original, some fettling was required to make it fit, but overall, it's perfect.
The main fitment issues are:
1. lower arm of radiator fan frame obstructed by chassis crossmember
2. power steering cooling bars need to be set back about 3cm/1-1/4"
3. new bracket required to secure top of radiator; probably not essential to have a bracket
4. thermoswitch positioned very closely to the chassis crossmember; original wiring plugs cannot fit because they protrude straight out from the switch into the crossmember; I will cut off the original plugs/terminals and fit 90 degree angle crimp-on terminals (no photos because I haven't completed this step)
Firstly, pics of the superb craftmanship.
I polished the top panel, which matches other parts in my engine bay better, compared with the standard brushed-metal finish.
Closed-cell self-adhesive foam rubber stripping used to seal against the car's opening.
This part of the lower arm is obstructed by the chassis.
I modified the frame with a new bracket, bent from 3mm x 19mm aluminium stripping. Additional holes were drilled to bolt it into position.
Frame was cut and pieces primed and sprayed in satin black, then everything reassembled. I sprayed the plastic fan with yellow engine paint, and the motor with aluminium coloured engine paint.
Modified fan bolted to the radiator plus new thermoswitch.
Top securing-bracket made from more 3mm aluminium stripping, which was polished. Neoprene rubber cut to size for a cushion between bracket and radiator.
Radiator fitted into car.
Bracket bolted to original fixing point.
PS cooling bars set back about 3cm.
The bars were secured with P-clamps, screwed to the original attachment points, with the addition of plastic spacers (not essential, but provided a little extra clearance). The modified fan frame clears the chassis crossmember.
Hopefully this helps prospective buyers of the radiator. The modifications are not difficult, but require a little thought and careful execution.