Thanks for the detail! Here is another method from a private message from another member who's done the diesel swap:

On my 87 Raider there was a vent line (1/4" I think) that went from the engine compartment all the way to the tank. It was right beside the fuel supply line. This is used to vent the fuel tank thru the carbon canister. I checked that there were no restrictions in it and used that as the return. It works perfectly because the unused fuel amount is very little.

As for the brake booster and vacuum pump I have the original D50 alternator with vacuum pump on the back. I used some of the steel pipe off the D50 and some of the existing piping on the Raider. I got some small of hose from the wrecking yard to attach up the pipes. Now the pressure power steering hose did require fabrication. I used the factory D50 pump which was not far off the Raider 2.6 gas pump. The return line was not a problem but the supply was different size nut into the pump. I cut the pressure line pipe in the straight area then cut a 1" long piece of pipe to slip over the two and silver soldered them up. You could use a compression style fitting but I preferred the performance of the silver solder.