Sounds like a very logical marketing plan. There was a W5 top end for sale at the Woodburn Mopar meet last weekend. The guy wanted $3500 for ported heads with 1.6 Erson rockers and a 4500 flanged MP manifold. Nice looking setup.

If MP won't do it maybe they'll sell you the core boxes! Make some changes to them and get into the head business. You'll probably need to raise $100K in cash or so to get it going but I bet you could make it fly. If you do one thing really well the guys will beat a path to your door.