J Heads?

One thing to remember in manufacturing, when something is replaced, for example head castings, the valvetrain part used in them have two options, Use as is or scrap. Since scraping parts costs money they try to consume the inventory until depleted, in this case intake valves. Factory to Factory controls were also not the same. Given the 340's performance only nature, the heads in ones hands, at one point could have been upgraded to 2.02 in the last 40+ years.

Of the 2.02 heads of every SB variety I have seen had the intake seats beat into the head where the 1.88 didn't. this is just what I have experienced and may not be the case for all heads as no two castings are truly identical, especially in those years.