64 camshaft help, please

[greektruck@xxxx]

hello ya'll. can somebody tell me please, i have a 64 300k short runner long 
tube rams, 390 hp version.. i am going to replace the 413 with a 440 or a 
500. i am going to retain the manifolds but know the cam must be the same 
duration to work with the rams. i read the response for the G, thats the type 
of amswer i am hoping for, i need to custom order this, and i know a 108 is 
cool, a 470 lift is good on computer, but what duration .050 and adv., the 
lobe centerline?. HELP!!!!!!!!!!!!! i know -4 at crank also. so grind 
straight up. and use 3 keyway gear set. please help me with this asap. i 
cannot find definate answers and time is so close. THANK yOU

p.s. i am going to use edelbrock heads