440 total timing

i dont know what kind of Tab there is on a bigblock to measure timing to but is it possible that its not in the right posision, or that the timing marks on the balancer is in a diferent posision?
if there is nothing else left i would try unscrewing the #1sparkplug and see if i could check if TDC is realy top dead center, my 318 had an old balancer that was way of and i found out by puting a screawdriver in the #1 sparkplughole and found out that TDC on the balancer was over 10degrees wrong, this may not be the most precise way of checking but i think you should notice if its of by much.. it took some patience and a lot of strenght to turn the engine over by hand but i found out;)