Not so;
X blocks are NOT limited to standard production block limitations.
Current-ish, are they even around anymore?!?!?!
LOL! NOT! But the following race block part numbers;
p4876381/789/671/791/673/793 are 4.220 blocks.
All are 48* blocks except the '791/793. There 59*
The 789 is a 48* aluminum block.
So, what block does our OP have? He stated a 4.160 bore all ready.