Engine selection, and why go type 4???

[BeetleTwinTurbo]

My origional idea has been trashed, and i'm lookin to start from the black board again. I'm in the middle of engine selection. I was thinking of a rotary, but everyone tells me that it will be to hard to run the lines for the rad, then I was thinking of type 1, cause it can be ready in like 1-4 weeks, then I was thinking of turbo or not, but as I've learned, people say that if you go turbo, you have to remove the engine lid, or space it out or what ever, I dont like that look.

so I guess its back to the old type 1 vs type 4, but heres the thing.

I dont really understand the differences between the 2, and why would a 2600cc(just an example) be better than a semi-full tilt 2332cc?

thanx