Well, to balance out the "keep it original" here, I do not agree that changing a 425/435 to an 602 is the same as "wrecking" the car. C'om on folks...
The 602 doesn't share parts with the smaller engines, ok. Obviously not the same, but in all fairness, they are similar. It's a matter of definition, and not so important actually.
Of the tree alternatives, the BMW, the 602 and building a 425/435 into a "602" or what ever..... Just using a 602 is CLEARLY the cheapest and easiest solution for more power. And regarding the question in the first post, is it hard to do, that's impossible to answer because if you're used to 2CV mechanics and have mechanical skills, it's easy.
If you're not mechanically skilled, and think changing a clutch is difficult, then it's difficult. So it depends!
And btw the car isn't more "wrecked" than it can easily be built back to original specs later for some reason.
Do one need more power? It's up to the user to decide.
To each his own, I guess. But one thing is certain, I enjoy looking at un-original cars, being just small details or totally mad max insanity
The "make it you're own car" thing in the 2CV community is very cool, even though not all custom cars are cool..
