Bugger, bit of a hold on the project

Nice idea, try reboring the block, or at least look into it. You may find it is a much easier method. How do the bottom ends differ? same bearings etc?

Main bearings are different, big ends are the same. Other than that they're indentical minus the clearance issues for the rods. To use the 2.0 crank in the 1.8 block you need to grind a few mm into the block wall to allow the rods to clear, the longer stroke crank itself has no clearance issues. I just wouldn't be happy using a block thats been butchered. I'd much rather weld up the head and leave it so the oil can drain down one of the existing returns.

The 2.0 block doesn't need to be bored, it would just need a quick honing (home job) The 2.0 block is also stronger than a standard 1.8 and alot stronger than a butchered one!

How is that so? What usually breaks on the 1.8?

Ok well in fairness i've never known one to let go but it's a mental thing, i'd really rather not have a butchered block.

I see no problems with modifying the head, theres a million places for the oil to return. If it was a feed to the cams or tappets i'd be worried a bit alright!

Fair enough it looks close, but is hard to tell from photos.