The 366 pattern is the same as the 350.
The 366 is a big block. Are you familiar with the Ford truck 330 and 360 motors that are are externally very similar to a 390/428? The Chevy 366 is a big block based truck motor externally very similar to the Chevy 396/402/427/454.
Might be a better choice than running a used 350 in your Jimmy.
