You realise it would never work?
There was a reason for the spacing of the spark plugs on the V8, simply following the same lines with the V12 would mean that you have two plugs in one hole. Or something.
Look at the way four cylinder engines get converted to sixes, the L16 Nissan being a good example. When it was changed to a six for the bigger sedans and the 240Z the spacing of ports was altered accordingly. Things like this affect spacing of spark plugs, so you have to look to the design to see what that spacing will be.
A couple of designs, first the Nissan:
Note that what they've done is put in porting the same as cylinders 2 and 3 of the four to become cylinders 3 and 4 or the six.
On the other hand, the 'Blue Streak' 6-cylinder version of the BMC B-series is more 'normal', with the newly included cylinders being the same as 1 and 2 and 3 and 4.
Now to look at the Lincoln:
Note that the valve order is such that it is essentially three 2-cylinder blocks in a row, each with the inlet ports in the middle flanked by the exhausts. The order is dictated by the need to get the exhaust to the outside of the block utilising the bigger gaps between the cylinders over the main bearing area of the lower block.
The Ardun heads used the same valve order on the Ford V8s::
And spark plug location is dictated by the consequent placement of the rockers:
Here's a picture of a Zephyr engine which clearly shows that layout for the exhausts, one in front, one in rear and two siamesed pairs in between:
So, if you follow this, you will see that your inner pair of spark plugs will come down into the head somewhere near the edge of cylinders two and five on each bank. To do it right there would be a pair of plugs in the middle.
