One benefit of having a spacer between the transom and the bracket is that it allows sufficient space for the engine to be tilted out of the water. I find that tilting the engine clear of the water when not in use is infinitely easier than trying to raise and lower the engine using the bracket.
When I replaced my bracket several years ago, I went with a model that fit on the spacer block. I had that option because my engine is a two stroke and doesn't need the new, wider base bracket. However, you can use the new wider bracket with your spacer block. All you need is to fabricate a "mounting adapter". I envisioned doing this once; I see the adapter as a piece of stainless (or aluminum, depending on the material of the bracket) that has holes in it corresponding to the mounting holes on both the spacer and the bracket. Mount the bracket to the adapter, then the adapter to the spacer.
If you do decide to go without a spacer, make sure you can get sufficient leverage from the cockpit to use the bracket to raise or lower your engine, or that you have sufficient room between the engine and the transom to tilt the engine out of the water.
