Factory Small Block Heads

1.88 J opened to 2.02 with a nice throat cut, better than an X. But that takes work. :)

Lots of early J's got 2.02's
Agreed. After so many years of popularity, you don't know how many valve jobs an X-head may have had until you get into the rebuild. The extra work required to go from 1.88 to 2.02 would be worth the time & effort instead of gambling on the X. 1.88 heads are usually cheaper too! A sunken, multi-valve job 1.60 exhaust isn't as critical as the intake (within reason).