Let us know what hex bytes you're patching, please.
Woops, yeah sorry forgot that indeed
The following are location and its new value (all words; 0100 = 1 and 0F27 = 9999). The original values one would have to look up as I'm to lazy right now but they were all dates from {1935, 1954, 1958, 1964, 1965} and maybe some other.
offset..........<- new value:
// the first block is in a function that checks against 1935 as lower bound
// and if "necessary" resets to 1935
0x0002AF3F <- 0F27
0x0002AF68 <- 0F27
// the second is the same as the first, just bounding upwards against 1965/66
0x0002AF81 <- 0100
0x0002AFAC <- 0100
// in the global header part of scenarios/save games there is some end date variable,
// that can have special values 0-4 and probably a real data
// in any case this block is switch on probably that variable
// where the first offset is for the default case
// it basically sets the endDate variable
// presumably this switch is used on loading
// Lightning's patch seemingly sets the default to max and redefines it for other cases (like 1952 -> 1958)
// I just hard coded all to max
0x0002DB39 <- 0F27
0x0002DB48 <- 0F27
0x0002DB5E <- 0F27
0x0002DB74 <- 0F27
0x0002DB8A <- 0F27
0x0002DB97 <- 0F27
// a switch of very similar to the last one though it not only sets the endData variable
// but also sets some probably local variable or a return value or something
// not sure where this is actually used
0x001036C6 <- 0F27
0x001036D6 <- 0F27
0x001036EF <- 0F27
0x001036FF <- 0F27
0x00103718 <- 0F27
0x00103728 <- 0F27
0x00103741 <- 0F27
0x00103751 <- 0F27
0x0010376A <- 0F27
0x0010377A <- 0F27
0x0010378A <- 0F27
0x0010379C <- 0F27
// in some unknown function it also hardcoded loads 1965 into some date related variable
// this could actually cause or solve problems... feedback about side effects needed
0x0027F99C <- 0F27
// this is the default value for the location the switches are accessing, so probably a variable endDate
// the value here is what is used when starting a new game
// and the end date you see in the "standard scenario from to most vp bla message"
0x0037AA14 <- 0F27
And the function call overwritten by NOPs in all the after 1964 AI disabling patches probably is a function or at least calls a function the checks for end condition being met and if so gets you out of the game (not sure whether also for conditions like in battle scenarios, one would have to check that). So if you only want time to not be a limiting factor anymore its just a crude hack not needed with the real end date displaced. The overwritten function call and the first two blocks is what makes up the 1964 AI disabled patches i checked. The first three and the last is what makes up Lightning's patch (i didn't check any others). Well that is about how deep i delved into the whole issue, there wasn't a need to go deeper yet, maybe with some feedback indicating problems I would look at blocks 3-5 in more detail.