This is my first attempt at a medium-lasting methuselah so don't be too hard on me
Hopefully it hadn't been discovered yet.
TBH I don't think anyone is really keeping track of this kind of stuff.
Also, the most efficient way to make mid-range (1 to 10 kilogens) methuselahs appears to be to collide smaller methuselahs (R, B, C, pi, acorn, etc.) with small amounts of junk. These are much less likely to fizzle out than compact patterns with a similar cell count. I ran a full analysis of pi + block and pi+ blinker(which can be rewinded to 8 cells) a while ago
which yielded 137 patterns that ran at least 2000 generations.
I've no idea how many compact up to 8-cell patterns that match the same there are (though this might be a completely enumerable set of patterns?) — but less than 5 have been found altogether, IIRC.