I like the connectors that vintage connections has, the density of the metal they use to make the terminal end is more than the ones that I got on amazon. Also the rubber sleeves they have are look more "period correct".
All in all it makes the wiring feel more secure. I almost broke down and rewired the engine harness again, i talked myself out of it, i forgot my reasoning though.
For most wires in the car I think 18 gauge TLX/GLX wiring will be sufficient depth on the length. I ended up ordering
https://www.wirebarn.com/11-Pack-of-18-Gage-GXL-Wire---------------------ELEVEN-11-Colors-25-Foot-Each-Color----------BlackRedBlueGreenYellowBrown-White-Orange-Pink-Violet-Gray_p_550.html
As well as some 12guage GLX wire for lines that draw more power... this wire is certainly better than the stuff at the local hardware store, for the price its probably cheaper too.
You'll want to get some open barrel crimpers to make this all come together, https://www.amazon.com/Crimping-26-16AWG-0-14-1-5mm²-Connectors-Terminals/dp/B00OMMZ502/ref=sr_1_21?dchild=1&keywords=open+barrel+crimper&qid=1628662108&sr=8-21
should do the trick, I like the removable dies in the crimps, at least if i start modernizing the engine harness i can go grab a new set of dies that match the terminal style.
Are the ends of the red wires melted? The blue plastic looks a bit weird.