I was afraid of that since the transom was only intended to keep the water out, not push the boat.

I found some pix of a sunchaser for sale that had pictures of the engines. Looks like a TIGHT fit for a pair of 5.0L Mercruisers. Might not be room for diesels of any size. Also, the transom has quite a curve to it. I'd re enforce the transom from the outside (as well as the inside) to get rid of the curve. Then add a pair of 300hp outboards on a bracket...the cost might be more than I want on a project boat. Still thinking about it though.