340 input (direction)

Not to be pessimistic..... but I would bet, based on what you paid for it (a lot less than what a properly rebuilt 340 (or any engine for that matter) and non od 833 is worth), that you have a backyard rebuilt 340 with a re ring and gasket kit. Likely it had a dingle ball hone run through it and original pistons and cam re installed.

At this point, see how it runs, if it uses any oil and how the oil pressure is at a hot idle. If all is good run it as long as you are happy with the performance. If you want more sell it as a running 340 and build a healthy 408. You will be miles ahead dollar per horsepower and can still look like a stock 340.