Car looks like it's getting some love. Are those yellow pieces from the original car?
As far as the transmission goes, I'm not sure the S-10 is the one you'll want. It'd be a great choice for your old Chevy pickup though. The 2 main issues being the shifter position is pretty far forward and they don't really have ideal gearing for a Datsun. 1st gear is between 3.76 and 4:1 depending on application. There's also the issue of the input shaft needing to be shortened (there's some more info and pics of this in my Compound thread). S-10 could be made to work but it really wouldn't be ideal. I think maybe a better choice would be a 3rd-gen Fbody. The shifter is in a more datsunish location, maybe even a couple inches farther back. The gearing is better too -- more of a close ratio. If you use a '84-92 Camaro bellhousing it will have provision for a hydraulic slave cylinder which may further simplify things. Be aware that they are canted a few degrees to the driver's side though which will move the shifter even closer to the driver and won't be centered in the console. If you prefer the shifter to be centered you'll need a different bellhousing with an adapter like this
https://www.novak-adapt.com/catalog/clu ... /kit-hcrc/ .
Edit: Be aware that the V-6 Camaro/Firebird transmissions are a different animal altogether. They have longer input shafts and a Ford style bolt pattern at the front of the case. Again, with enough screwing around they could be made to fit but it isn't really worth the hassle. You need to look for '83-'89 305 Camaros/Firebirds. Up to '92 will work but has an electric VSS speedometer drive.
When the only tool you have is a hammer every problem starts to look like a hippy.