I have a 65 Barracuda with a slant 6 - three on the tree want some transmission/engine advice

LOL You DON'T want me to restart the "I can drive a non syncro 3 speed rant"
How well I know. It's just a non issue with the clutch adjusted correctly. Even Kitty has no problem whatsoever finding 1st gear while still rolling. It's just not difficult at all. I've never understood all the whining either, but there's a lot of it. Not talking about the op here.