Do the wires from Cylinders 1&3 go above, through or under the motor mount? Also, do they go between the exhaust manifold and the engine, or on the outside of the exhaust manifold?

I've seen a lot of them run through the motor mount, and between the engine and exhaust pipe. The '81 was set that way. I re-did them the same way. It's a little tough feeding them through the motor mount, but it can be done.
I did a little extra on mine. I got some of that black corregated plastic conduit 3/8 inch diameter, like they use under the hood of newer cars to protect the wiring. Works great for preventing chaffing on the plug wires.
There is 2 different types of conduit- "Under the hood" for high heat and generic conduit for interior wiring which will melt.
Have fun!
Sarge

What Sarge said, and agree that it is a real P.I.T.A. to do. But once all the shiny shielding is back in place it sure do look purdy!