I built my 428 HP 340 With edelbrock heads for rite around $2300-$2500. If I went with my X heads it would have been about $500 cheaper. I say 340, but I also have 9 spares with tons of 340 parts. I thought about building a 360 because the longer stroke will deff. produce more torque. As far as cost the 340 is not that much more to build. Only extra cost is the cost of the block. I know up this way 360s are a dime a dozen but you mention 340 and peoples eyes really light up. All personal preference, but id go LA all the way. I just sold a 70 375HP 340 ported 2:02 Js, steel crank, forged pistons, 10:1 comp., 280/.480 cam with only 1000 mi on it for $1800. Guy put it in a barracuda and is happy as heck.