A833 4 speed 86 truck?

I think you could save yourself some real coin if you have the fabrication skills and tools
to cut, weld and drill/ screw this together.
I have taken those truck OD transmissions and fit them Into plenty of vehicles that they weren't meant to be installed in. I almost always put them behind a 440 myself but any engine you have the bell and flywheel for will work.
Sounds like you have all the parts from the truck donor, that is what makes it a economical
choice.
One of the benefits of a fab it to fit job like this is you can mount the shifter box closer to the rear if you have bucket seats and use a short stick for a short throw in a comfortable no reach position. Put it where it feels right to you when you have your seat adjusted where you like it.
You will have to make the shifter box mount bracket, modify floor pan and remake the shifter rods starting with the ones you have. Cut and weld tire irons between the factory ends to get them to the length you need them to be. The short e-body handle could be used if that's what you like.
Here is a picture of a truck setup modified for a street rod project to give you a idea of what
can be done. Those rods used to be tire irons, make them any length any bend. It has always worked for me.