I know nothing about the Shimano Deerhead, but your description of the Suntour Cyclone behaviour is not atypical for 70s-80s vintage equipment. Part of the required skill back in the day was developing the finesse to shift from one gear to the next, accurately. With practice you whould be able to acquire this skill. There may be some esoteric adjustments that could possibily improve your shifting performance; with some expert assistance and/or trial & error on your own, you make be able to eke out some improvement. It is pretty much a given that the front derailleur will need to be trimmed slightly to accommodate the variation in chain angle from the largest to smallest rear cogs. By this I mean you need to trim it as you ride, in accordance with changes in the rear derailleur position.

I've heard and experienced that Kool Stop Salmon pads are more prone to squealing, and whether it occurs or not seems to be a little be hit-or-miss with each individual installation. You will find that there are a few threads dealing with this if you undertake a search. The immediate steps I would take to investigate this issue are:

• ensure pads are adusted in proper alignment with the rims tangentially, and square to the rims or slightly toed in from a perpendicular perspective with respect to the axle.
• ensure there is no undue free play in the attachment of the brakes to the bicycle, or in the fork assembly to the frame.
• if the bike has not been ridden extensively for a while, it could be a matter of bedding in the rims. Some judicious hard braking, e.g. going downhill should take care of this, if it is indeed the issue.

As a last resort, change to a different type of pads, but, speaking for myself, I can tolerate some squealing in exchange for the improved stopping power of the Salmon pads. Squealing brakes can also serve as an automatic warning for errant pedestrians as well as fellow cyclists.