almost all 340/360 heads flow the same. cept' for the X-head. doubt you'll find one of those for under $1000. i would
suggest using the "302" cylinder head. clean the bowls, port match it, and put in some 2.02"/1.60 valves. you'll love it.
pistons as you said, go the the best you can afford. cast cranks are good for about 550 donkeypower or 500 hp
whichever way you wanna look at it. ONCE you decided what you really want, build it like anyother normal 318.
PS
no need to champher the intake side of the bore with the 302 head.
PSS
dodgetkboy78 had some pretty good advice.
