best fit under smooth cowling

Here is a question which must have been asked before, but I cannot find the answer.
I am coming up on ordering the finishing kit and need to figure out what engine to specify.
So far I am leaning towards a parallel valve IO-360 with forward facing fuel sump/horizontal induction.

Given this starting point, what engine fits best under the cowling of an RV-7a?

With "best fit" I am primarily looking to avoid "surgery" on the factory cowling.
It sounds like (and one would think) the original Lycoming IO-360/180HP as sold by Vans fits without any cowling modifications?
If that is true, what other engines fit the bill? It sounds like the superior cold induction requires surgery (a cut in the cowling)?

Depends

If you are a perfectionist then the selection does not really matter because none of the choices fit without fiberglass work over and above the steps noted in the building instructions.

I only have experience with the IO-360-M1B (180 parallel). The cowl did not need surgery to "fit". There is plenty of cowl clearance everywhere. It DID need surgery to meet my cosmetic requirements.

The internal snorkel provided for the filter on the left inlet ramp needed a LOT of surgery. This is a late model piece (I read there have been some revisions) so you should expect the one you order to be similar. While some people have cut and hacked like I did, I think some have not. I was not satisfied with the fit on the -M1B out of the box. It MAY fit an angle valve out of the box since the angle valve is a wider engine.

I have the Superior

180 w/ cold air fwd sump. NO cowling mods required, but I did have to workover the snorkle (not too hard, really). I installed Vetterman 4 pipe exhausts which results in a very clean install. Cable brackets were simple and neat, and all work well so far.