Sumo, you can get some inspiration from a copy of Iron Horse Issue #130. That is this month's issue and it is on the newsstands here in America. It has an article about Paul Friebus, a fellow from South Africa, and his Harley flatheads. He is running them at just under 140 mph at Speedweek. That is amazing, all considered.
Maybe it would save time and money to develop a single engine Panther, then, after everything is perfected, to build another engine for the double. This would save a lot of time and money. Just a suggestion.