You should be very PARANOID about lifters......
i also destroyed a very strong running 511ci this past March 2008. ( broken lifter)
roller ball broke off the lifter on the #1 exhaust , wiping out cam and block
car never mis-fired etc...it just became lazy....i am sure it was just a matter of time ( seconds/minutes) before the engine just seized up but i discovered it in the pitts before it got the chance...
Now $6200 later i almost have my new 565ci back with Dart Big "m" Block,new cam,lifters,rods and pistons from PAR engines...
i could have done without it.....my 511 was just fine..
whats so scary to me is that i do not know of any way to detect a lifter about to dump on you unlike detecting a weak valve spring etc.....
Sorry to hear about your loss but i relate all to well.
thanks
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "