OK, so Mark's pdf is 157 pages long. Sorry, but I just can't read all of that. Those that know me know that reading is just not my thing, but I wanted to at least make some effort since I said I would do so, and the topic is interesting.
I tried to skim it using significant words like "Fathers", and it seems as if the general gist is that there were certain early Church Fathers that believed in a 1,000-year reign of Christ prior to the End and other later Church Fathers that did not. This 1,000 year reign, according to Sungenis, would allow for a mass conversion of the Jews, but because the Church ended up taking the latter view (that there would be no such millennial reign) there would be no time for a mass conversion to happen.
I did not see where Sungenis shows that it is definite Church teaching that there will be no such mass conversion. Maybe I missed it given I only skimmed. If so, perhaps someone can point me to it.
At one point, in refuting Fr Mawdsley, Sungenis writes that he could not call a letter by Pius IX "magisterial". Why? Because the letter is not listed on the Vatican site. He does realize that the Vatican site is run by a bunch of Modernists, correct?
Anyway, given various Church Fathers seem to have had different views on it (and the Church does not appear to have decided one way or another), I walk away from this topic thinking that a Catholic could take either view.