budget 383 build!

Ok guys starting over.. I bought the 71 383hp and it is mostly original - It has been resealed basically.

SO I plan to tear it down to inspect it and reseal it - going to add a double roller timing chain, small cam, valve springs, performer RPM intake(or Mopar equivalent), shim head gaskets, underdrive crank pulley, and a retrofit high amp alternator for an electric fan and relaying the head lights (makes them brighter)

Looking at a Comp 270H (224/224 @.050" / .470" 110*)(run Comp springs from my other "346" heads), Weiand Action Plus intake, Holley 750, and Heddman 1 3/4" headers, 2.5" X pipe/ dynomax ultraflows. stock electronic ignition and probably a 2500 stall

Which I need help with - everything I look at is neutral balance, why are there not balanced flex plates/converters? Must they need to be balanced after purchase?