Ford Sierra Trackday Racer

I was going to build this Sierra XR-4i mostly stock but with custom wheels. Then I picked up most of a RS500 kit, minus the body. The chassis is nearly identical, so I can fit most of the cool racing parts onto the more sedate road car. The major exception is the engine, as the RS500 is curbside whereas the XR-4i has an opening hood. The V6 that comes with it is kind of boring, so I'm planning on an engine swap from another Ford kit.