Synchronized Tree speed

[MS66]

My truck is a '68 C-10 with a 250 and non synchronized 3 on the tree. I have a question about what 1st gear synchronized 3 speed gear box will be a direct swap. I want to keep everything the same(or very close to it) on the column shift linkage. Can someone steer me in the right direction where I might can find this information, my google powers aren't bringing any useful info yet. Thanks for any help.

FWIW, the 3 speed in my '69 G-10 van has synchronized 1st gear, it is spoiling me. Same engine as C-10.

EDIT: I found some useful info. My truck has a light duty Muncie 318 non synchro, seems the Saginaws are synched. Are all the Saginaw 3 speeds synchronized in first gear?
I need to rephrase my question, what all will I need to swap a Saginaw in place of the Muncie 318? Is it a feasible swap?

Found some more stuff. This is a pic off the internet of the transmission in my truck, Muncie SM318. OAL from bell housing to end of output shaft is 16.5".
Member 68gmsee on here did this exact swap long ago. He hasn't been on here since '22. Not a good sign. Hope all is well.