Most everything fits as if it was made for the car the only down side is the limited space for the radiators and such. Would of gone with a hydrobooster but this engines have no power steering pum.
The engine and trans are in. That is as far as I have gone, stopped there need to figure out the braking system at this point no room in the engine bay for a booster so any ideas would be greatly appreciated.
newer engine in older car is ok as long as it retains all the emission components but they have to be legal engines in ca those two are a no go for emisions
usually when this trans are run low on fluid they tend to scratch the bearing causing the noise. The main input shaft bearing specially, also the rear counter shaft bearing is notorious for failing. So more than likely they are both bad i tried to post pics but couldn't but if you take the front cover like the above pic and see any change in color in the metal then a rebuilt is at hand. They are really simple to fix if you have a press or large bearing extractor.
The switch that goes on your pedal dude so you can start your vehicle that's how I did it there is always other ways of doing things as for the 720 accessories fitting a d21 no clue I had a truck for spares so I used everything of it. Now I just finished rebuilding the auto trans I will post pictures of the what's needed.
That you are describing sounds like your input shaft bearing is going bad for that matter all your bearing. I just rebuilt one with the same symptoms I will try to post pictures of them latter.
Cali smog sucks, but nice ride. Things to look for on the truck are thermostat gets stuck and it leads to overheating, freeze plugs driverside cylinder #4 check for rust and pretty much you have the rest. Overheating is the main issue due to what I mentioned.