Just a little detail on yesterday's momentous activities...
Having rolled the car out of the garage we removed all the spark plugs and turned the car over on the starter. With the plugs out it meant there was no compression and it gave the starter an easier job turning the engine over and so get the oil moving around the engine. The starter worked hard but it did well and the oil pump managed to (eventually) fill the huge oil filter and then we got a reading on the oil gauge.
Whilst we were at it, we proved there was a nice fat spark being generated.
Next we decided to go for gold and put the plugs back in, I connected up the second battery to power the fuel pump then reached for the key. At that point petrol leaked out of the hoses between the carbs and we had to abort. When I put the carbs back together I inspected the hose and it looked OK, but it turns out it had become quite rigid and no longer compressed properly when I clamped it up again.
Luckily I bought some new hose the day before because I needed some when I replaced the pump. So we swapped that over and this time all was well.
We turned the engine over for quite a long time, giving the starter and battery a bit of a breather a few times. But, we got some encouraging coughs and splutters as one by one each cylinder came online. Finally it was running on all 6!
It's a real shame the fan was catching the bottom of the rad again when it was running at speed because it sounded awful! But, it was running well enough for Dad to tweak the screws on the carbs to a point where the engine would idle and pick up relatively well.
I'll post up an edited version of the video footage we took when I get a chance.