Combo Advice 340
I would go with Moper. Stroke that thing!!! A 340 bored .040 over with a 4" stroker crank would be a 418. In a 68 barracuda that weighs about 3100 pounds with a 200 lbs. driver, it would scream. My 416 in my '69 dart is putting out about 500 hp at the flywheel and runs 11's weighing 3400 lbs with me in it. You could possibally dip into the 10's with traction and a good driver. Good luck.