I think 1.66
The issue is, even back then, Ford didn't worry much about quench. (3.98/2) + 6.49 rod + 1.66 = 10.140, the deck height was 10.170, that puts them .030 in the hole before a gasket, and even if they were 1.67, they'd be .020 in the hole.
Personally, if you were in the .055 quench range, I likely wouldn't even think twice about it if the compression came in where you wanted it, just be careful on cam choice, mixture and timing, but to do that with a Felpro 1020 gasket at .041, you'd need to cut the deck to 10.151, and if you went with a Blue Felpro 8554, you'd have to cut to 10.142 or so, which is a pretty good cut.
The 1020 option isn't horrible, lots of FE decks at 10.150, but I tend to try to stay at 10.160 or 10.155 when I can, just because I hate to cut more than I need to