When you say the "new chassis" are you refering to the Mazda3 car?
Also how reliable is a N/A PP 20b producing 400+hp? How may race hours between rebuild and what would need changing?
If running fuel injection you would be looking at around Â£25,000.00+ for an N/A PP 20B with around 450hp. It would require a refresh after a season of racing in club class types of racing where for example races were around 20 mins with similar qualifying.
That having been said it could also be built with around 400 hp for endurance racing and should be able to last for a 24 hour race before needing a refresh.
We had a 2 rotor engine that did 2 full 24 hour races and 11 hours in a 3rd race before the car had a serious incident with a Porsche and then after being repaired it still did alot of Britcar races with no rebuild. It eventually covered more than 10,000 race miles before needing a rebuild. Power was 365 hp with turbocharging in a power to weight limit.
Refresh prices are alot less than the initial outlay.