I allways made sure I put a good double roller timing chain on my small block chevies I built. Though the engines may be more complicated now than in the past they are still the same when it comes to push rod engines.......
Your push rods were replaced right? they are likely to have been bent and stressed....Did you look at your pistons? Valves can bite the top of pistons pretty hard, but you did not really skip timing as compaired to loosing it all together. I do not know if the pistons come with reliefs in them and if they are domed or flat of what.........People need to know that aluminum expands and contracts more than cast iron so heads and other critical tolerances need to be retorqued.....I used to do them every 50-70 thousand miles on my cast iron blocks. And throw out old pitted performance intakes that pit from the antifreeze over time..( like 100K+). unlike redecking a head the shaving of a intake is not an option. And retorquing the headers was a every few months task due to thier expansion and contraction and the shaking of the engine ......Oh how I miss the nice lope of my last 406....well my zl1 will fix that. Good luck to you...I would want to look at the engine when it was tore down if it was me is all I am saying to check the cylinder bores and pistons etc etc and make sure i had a magnetic plug in the fresh oil in the pan.