NEED HELP

[SADISM]

I AM NEW TO SITE AND NEED SOME HELP, I HAVE A 89 GMC 1500 REG CAB TRUCK. I PUT IN A 1970 LTI 350 BLOCK, CRANK, AND RODS, TOOK OUT THE DOMES AND PUT IN FLAT TOP. I PUT IN CAM WITH SPECS 204/214 DUR@ 50 AND LIFT OF 420/442 . I AM RUNNING STOCK 89 76 CC HEADS WITH 550 Z/28 SPRINGS. I AND RUNNING STOCK 89 INTAKE MANIFOLD AND STOCK 89 EFI. I HAVE STOCK 89 DISTRIBUTOR AND AM NOT RUNNING A KNOCK SENSOR. ALSO STOCK 89 EXHAUST MANIFOLDS AND 2 1/2 EXHAUST AND NO CAT WITH A TURBO MUFFLER. I AM GUESSING THE TRUCK SHOULD HAVE ABOUT 280 TO 300 HP. BUT IT DONT I HAVE SET THE TIMING BY WARMING IT UP AND TURNING THE DIST TILL IT MISSES THEN BACING IT BACK A HAIR. ( FULL ADVANCED ) THE TRUCK HAS NO POWER AND HESITATES WHEN YOU HIT THE GAS. IT WONT EVEN SPIN THE TIRES. IS THERE ANYTHING I CAN DO OR IS THE KNOCK SENSOR MESSING WITH ME. ALSO THE TRUCK IS BACKED WITH A TURBO 350 TRANS. IS THERE ANY HELP THANK YOU ZAC