There is a fusible link in one of the main supply wires, which is basically a wire that a fuse. Also check the battery terminals. My sons 68 C10 would light the dash but not crank. Discovered the negative terminal was corroded between the terminal and ground wire clamp. As soon as I cleaned...
Probably the proportioning valve got tripped, therefore not letting fluid go to the rear brakes. It should be on the front crossmember on the right side.
Did you check that the wire to the electric clutch didn't get unplugged when you were dealing with everything else? I had one spit completely out from under the mower on a JD320. Ripped the connector off.
Keith's suggestion is what I did in my shop. The problem is you would not he able to use the short rail you have. I had to go with a 24ft I beam and a pair of 10ft 4x4 square tubes for the uprights. Plus it runs side to side instead of front to back. Not as handy for things like engine pulls.
It's pretty simple. Remove the two nuts that go from the rag joint to the steering shaft. Then you can pry them apart. Then remove the bolt that secures the rag joint to the steering box output shaft and pry it off. Install is opposite.
Also watch as they make 2 different ones, they have...
After fighting it with soapy water and a glass install stick, I got about 18" done. Went to O'Reillys and got the install tool. Think it took about 10 minutes to get the rest done. $15 well spent.
Look at the transmission pan. If it's basically a rectangle, it's a 700r4. If it looks like a square with a corner cut off, it's a th350.
A search of chev automatic transmission id will give you pics.
Get a white sheet from the thrift store and spread it out in your workbench to disassemble the carb on. Makes finding tiny parts much easier. Spray carb cleaner through every nook and cranny . Take your time, take lots of pics, and you will do fine.
How high? Intake or carb leak will cause it to run high. I used the wrong base gasket after a carb rebuild and it wouldn't idle below about 2k. Major leak.
I just converted the factory AM radio in my 70 C10 to Bluetooth using a $20 Amazon Amp. I gutted the old radio and mounted the Amp so the original on/off/volume rheostat would control it. Someone else had the idea you could just wire the Amp to the power wire for the radio so it would come on...