Grinding when downshifting

Hi, new to the forum, recently picked up a 65 barracuda 4 speed with 273. Recently got it running, but now i'm noticing some issues with the transmission.

Shifts fine when I'm upshifting thru the gears, but everytime I go to downshift from any gear, I'm getting grinding. Think the synchros are out?

I dont know much about these transmissions, or any transmissions for that matter... If it ends up being a major repair, is there a better transmission to swap in favor, or should I just plan on rebuilding it?