Here's a little close up of two of the issues that we had fitting the larger engine.
Firstly the engine was longer.
Secondly the exhaust spat straight into hood. It really kills the paint.
Here I'll show the extension and later some better pics and much later (when the rain stops) I'll outline the exhaust solution.

[Linked Image]
Here you can see where the bonnet hinges and further back a bolt.
Just forward of the bolt in the original tinware was the mount for the bonnet (hood if you're a yank).
I made a pair of brackets from some scrap 2mm plate which moved the hinge point 65mm forward and 20 upward.
I used the rear bolt holes to hold the brackets to get perfect position and then welded through the original hinge holes to the brackets.
Then of course I dressed the welds and primed, prior to final paint.
In the top left you can see the problematic exhaust ('zorst if you're a yob). The small spot welds holding the baffle were dressed back clean with a Dremel (I love my Dremel) so the deflection pipe would would fit cleanly, I'll show that in the near future.

Quality is a direct experience, independent of and prior to intellectual abstractions.
R. Pirsig .