No stupid questions yet.
I think I'd use the complete Gordini engine because the cams are different, and the Gordini uses a cam bearing in the block. That's not to say that you can't mix and match as I've fitted the bearing into my GTT block. You will almost certainly need to modify the head to fit the water pump on the back of the engine, or use a Turbo 2 head...
You'd need to make a plate to bolt the GTT carb onto the Gordini manifold, not too tricky, and it's been done on more than one Gordini.
You'd probably want to make an exhaust manifold, or have the turbo sat over the gearbox, and have to move your tank etc.
I couldn't say for certain on the unleaded, I run it, but then I don't do many miles.
if you ask this guy nice he might show you some pictures of his engine.
https://www.rtoc.org/boards/member.php?u=325