Crosswind makes an Edelbrock knock-off intake for a reasonable price that will work on either LA or Mag heads. You can use the LA flywheel and headers. I wouldn't waster my time with the LA exhaust manifolds which would probably leak anyway due to the AIR injection ports. Use the Mag serpentine belt/alternator/p/s pump setup. Can't run A/C with the crosswind intake anyway due to the old style thermostat housing location. You will have to trim off the A/C compressor mounting pad for clearance. However this will require an electric fuel pump mounted by the tank to supply fuel but makes for a much cleaner swap IMHO. I should also note that when using the 120 or 136 amp magnum style alternator a fused 10 ga. shunt wire should be added between the alternator and battery to prevent overload of the factory amp gauge and bulkhead wiring in your 85 truck.You will be amazed how much better the mag motor runs compared to the old tires LA.