E30 325e vs. 318i

[Aether]

I'm planning on buying an E30 later this year, but I'm still undecided about the model. I'm looking for a pretty cheap priced car. Even though I live in western europe, the 325i is pretty (too) expensive for a cheap project nowadays.

Within a year I'm planning on dropping an M50 engine in it (possibly with turbo), so engine power isn't really my concern. I have the following questions regarding this project:
- Does the 325e share the same suspension components & stiffness as a 325i?
- Is the getrag 260 gearbox from a 325e the same as the 260 from an 325i?
- The rear axles and differential from a 318i appear smaller than from a 325i, how are those from a 325e compared to these?

Basically, what I want to know is which of the two is better for a project like this. Before you start a 'buy a 325i' flamewar, the price difference is about 3000 euro's between a 'good' 325i and the 318i/325e versions. As I won't be using the engine for long, choosing one of the others seems cheaper.

But I'm open to any suggestion. Thanks in advance.