340 build help

I have learned to never trust what someone else has done or says it has been rebuilt or only has XX miles on it. Usually has been BS from my dealings, so If it was ME, I would pull it apart and take it to my machine shop and let them inspect it, and the very least put cam bearings freeze plugs in it and give it a really good bath, hone cyl and polish crank. Go through heads and check guides, measure springs valve guides. For me that is cheap insurance knowing that the internals are good and will last a long time.
After the machine shop does its magic, A Voodoo cam kit, oil pump, Eddy RPM intake and a HOLLEY 750 and HEI conversion. You could also get a slight return if you put your unused parts on the NET to sell for a few hundred dollars or so.
Good luck!