No its not. I've followed very closely MANY engines ('cuz I'm interested in this stuff) I've built and dynoed (SF-902) over the years when they wind up on the rollers or even better a chassis dyno that bolts up to the wheel hubs (my fave). They typically put down about 90-100 hundred HP less than what the engine dyno shows. He's bang on with his 340 hp estimate--I've also tested 340's that are similar to the OP's and they make 340-360 hp everytime. It scales up and down very consistently--I built a 471 BB 682 hp on dyno--in car made 587 hp at the tire with a TKO 5 spd--that's pretty close I'd say. Did a 360 with Eddy heads small cam made 402 hp and in car made 312 @ tire. J.Rob