If you can find a good manifold, the carbs will give you a better tune. Webers make a lot of noise at full throttle :) A couple of SU's will be quieter and still put out.

Montana has great secondary roads, so take them if you are able. Interstates will require you to maintain at least 65mph. The injectors are probably very dirty so your mpg should not be good, stop for gas often and give the engine a chance to cool.

You will pass through storm fronts, make sure the wipers work before you leave. You might want to consider getting four very cheap tires, the current rubber may be dry rotted. Snow tires will last the trip and will make great winter wheels.

Get some duct tape and baling wire. A standard 1/4 screwdriver, phillips screwdriver, pliers can do wonders. Especially when the points burn together.

Lots of luck, and have fun!!! I-90 is boring, Chicago is hair raising (might want to consider mounting a slow triangle on the rear bumper?).
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My back feels better when I sit in a Volvo seat