There are several possibilities with your too-short pin. Maybe a longer stub could be welded on, maybe you could get a junk Mahindra end with the ball in it and grind the ball down or maybe you could just get a whole new tractor lift arm off a similar tractor. I'll bet a lot of them and probably different brands would fit. That plow cross bar is a common item in boneyards and I'll bet you could find one. There isn't a great demand for 101 parts and once damaged beyond use it isn't worth putting the $$ into them. Welding a stub on is probably the easiest and the greatest help towards resale.
On tightening the plates up, you don't want to crank them down tight but to take the excess slop out so you don't twist things. That's a judgement thing and loose bolts cause problems. On the oil on them, the spring trip models have grease fittings to lube the shank and the owner's manual mentions to grease to prevent a fail to trip scenario that bends things. Maybe the trip model is different. Same with the shear bolts. I have never owned a trip model like that so be careful to use the right bolts so the thing trips. In roots it will trip and you sure seem to have the HP to pull it. Most 101's were blue but I think the very early ones might have been Ford early Rouge red and not NH red. Yours is likely blue. Buyers are drawn to the right colors and steer clear of the wrong colors.
No plow is "best" as is no tractor is best. Widely regarded as best, however would be Kverneland but you aren't likely to find any in Texas and need experience to not buy the wrong one. Their long sweep moldboards pull easy and their plows have won nearly every plowing championship for the past 50 years.
The most practical best for around my area would most likely be an Oliver, White or their clones. I think the Ford 140 is a White/Oliver but not sure. Find a tillage catalog and see what parts are common to each other and that's a good start. Old Deere plows pull hard but are loved. IH plows run the range and are well regarded. Generally, the plow, because of it's exposure of soil to erosion has mostly faded away in favor of the chisel plow that fractures the ground, lessens compaction issues and is faster with less fuel use. The moldboard plow is a sometime thing where soil inversion has a use.
I have owned a lot of plows and for me it's no more. I have a ripper and chisel plow and that does everything I need in the Midwest black dirt/clay. Still, I would like to find a 3X Kverneland, convert to 2X and pull behind a smaller Kubota for gardens or whatever. Maybe just restore correctly and look at it from time to time. They are a work of art--and parts are priced accordingly.
For whatever reason, I really am drawn to moldboard plows and have owned a lot of them. Maybe it's just about the chase and not the end game?
Here's an example of the correct red below--look how it pops--although I'd bet yours was blue. If you paint it blue, Ford factory paint is excellent quality and the best paint for the money in my view.
