No start 340

Got My 340 rebuilt two years ago with a lot of good parts set of X heads cast iron, custom dome Ross Racing pistons big cam and value springs and so on. It made 490 hp @ 6900 rpm on the engine dyno at the shop In Jupiter FL. J & J Balancing that built it. Wow I was very excited to put it in my 70 duster back half car for some Bracket Racing. (Just retired from the FEC railroad after 35 years ready for some travel with my car to all the grate drag strips east to west) but I’m stomped? It took a year to finish the car and now it won’t start got spark, fuel, Compression it just sputters like it only fires on some cylinders. Got all new MSD 7-Al box, coil, distributor checked all plugs all have fire 1 8 4 3 6 5 7 2 , checked TDC on #1 multiple times. I even got a new old school points distributor and hot wired to the battery. Still got the same problem. I can sweep the timing (turn the distributor 180) with no back fire, got to be a timing Issue. Love my Mopar but I’m at the end of my rope