Have engine builder here I work with take wayyy too long on motors before. I refer him work- he does a great job- but gets wayyy behind a lot. sometimes 6 months +... but always comes through. I hope that is all you are going through....
But if it's not... if he is scamming you....
Get doc's/ facts from the builder NOW such as: parts list, costs/labor, invoice info, etc... I would demand it now... prior to paying another dime. Prior to accepting the motor, get info & pics. In the mean time, check the parts list & begin getting parts jobber/dealer parts prices (just to compare something). How the hell do you forget a timing chain???? Bring a camera to the p/u location... pop the valve covers... know what you are looking at. File a claim w/ BBB prior to p/u in case you need to show a pattern/problem in the future. Get as much info as you can VIA E-MAIL... you may need it in the future. Demand to see it NOW regardless of any more money needed. Next call should a to schedule a appointment to see the motor & discuss completion or suspension of build until you feel it is right. Good luck!!!