best cylinder head

as of current the car this 340 is in ran 12.27 at 112. it is a stock suspension car essentially and was going through the traps at too low of an rpm like 5900. RX302S-R6 is the camshaft and they have a ton of portwork done to the heads. my car is a 69 dart which we are building. it will have an all out tub job, frame rail work, 10 point cage, dana 60 with 31x16.5 dot slicks 5.38:1 gears, 4 speed with a scattershield and all that and a vertigate setup. also a cool fact about the dart is it is the number 1 dart off the line from L.A for 1969 sequence number 00001. factory radio delete car with the full trim piece on the dash and everything. turqoise with a white top

"my car is a 69 dart which we are building." Have you actually driven a car with this engine?