WOW. I feel yo pain. That is the same thing that happened to my engine on the last rebuild. Had to tear the engine completely down & rebuild. Not too much damage, just the items that were related to the timing gear etc. (cam, some valves, push rods & timing gear & chain). All back together now & seems to be running good. Went to Sage Raceway in Idaho Falls last weekend (1/8 mile track). Best time was 7.55 & 90 MPH. Corrected AD was 7300 feet so that is a pretty good time considering. Believe the engine to be a little faster than my previous build. Good luck on your rebuild.
Joel