Cut 6x heads?

I have a 74' 455 that was rebuilt and then maybe has a few hundred miles on it.  They put 6x heads on it way back then.  I went to swap the intake for an old torker I had here and it won't fit.  My question is how much would a 6x need to be cut before you would have to cut the intake?  This is a serious mismatch but I might only need to take .005 off each side and it will fall right in.  To give an idea I can get one sides bolts in and the other side you can see the hole in the head is about 3/4 the way up the intake hole.  Or maybe the block was cut?  Is there anyway to measure something without having to pull the heads and cc them?  I just don't want to have togo back to the machine shop and pay him for everytime we cut alittle more off.  I think I'll be paying him at least twice since the crossover is cut off and also needs a trim.  

If you have a factory intake at hand see if that fits first.  

General rule of thumb I have gone by is .030" off the heads means it's time to shave the intake also. Some say .020". A human hair varies from (approximatly) .007"-.0010".. The human eye can detect .010" difference. If the intake doesn't fit, I would presume at least .020" has been taken off the heads. Most good machine shops will stamp the  amount cut on the surface of the heads, so to be sure, it might only cost you a set of head gaskets.  
Jim,

+1 on the .020.
If .020 was removed from the heads most likely the intake will need to be cut as well.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races