Can someone tell me if this is a horribly difficult task, or an easy task? My 1963 has a really slow fan motor. My 1960 has a really good one. And someone on ebay sells brush kits for the motors.

Not too bad- you'll need to pull the whole heater unit. Remove the lower ductwork screwed to the floor/ hump, drain the heater unit (as well as possible), disconnect the three hoses under the hood, disconnect the plug, disconnect the heater cables and clips, pull it out. I'd remove carpet as you'll lose coolant inside the car.

__________________
1968 230S Automatic, Elfenbein
1975 O309D Executive Westfalia Camper Bus, Blau/ Weiss
1972 280SEL 4,5 Dunkelrot
1966 VW Type 34 "Grosser" Karmann-Ghia
1963 VW 1500 Variant Pearlweiss
1969 VW Variant Automatic, Perugruen
1971 VW Squareback Automatic, Clementine Orange
2001 E320 4Matic Wagon- Our belated welcome to the 21st century! Polar White
1973 280SEL 4,5 Sliding Roof "The Bomb", Dunkelblau.

Are there related parts that I should replace or check at the same time? Do heater cores go bad in W111 cars?

Anything "can" go bad, but it's not usual. Get some genuine heater control valve O rings and clean/ lube the valves with new rings. Note valve position.

Replace your short water intake hoses at the top with top quality hose.

__________________
1968 230S Automatic, Elfenbein
1975 O309D Executive Westfalia Camper Bus, Blau/ Weiss
1972 280SEL 4,5 Dunkelrot
1966 VW Type 34 "Grosser" Karmann-Ghia
1963 VW 1500 Variant Pearlweiss
1969 VW Variant Automatic, Perugruen
1971 VW Squareback Automatic, Clementine Orange
2001 E320 4Matic Wagon- Our belated welcome to the 21st century! Polar White
1973 280SEL 4,5 Sliding Roof "The Bomb", Dunkelblau.

I know on the W110 there is an access panel on the firewall that can be removed and you can see (but not remove) the blower motor.

It is possible to lube the bearings of the motor through this access plate to some degree. You might check to see if you W111 has such a plate. Perhaps you can treat the problem with less work than you think.

Some early cars have this, later cars do not.

__________________
1968 230S Automatic, Elfenbein
1975 O309D Executive Westfalia Camper Bus, Blau/ Weiss
1972 280SEL 4,5 Dunkelrot
1966 VW Type 34 "Grosser" Karmann-Ghia
1963 VW 1500 Variant Pearlweiss
1969 VW Variant Automatic, Perugruen
1971 VW Squareback Automatic, Clementine Orange
2001 E320 4Matic Wagon- Our belated welcome to the 21st century! Polar White
1973 280SEL 4,5 Sliding Roof "The Bomb", Dunkelblau.

Thanks. I only have experience on a few 1962 and earlier ones.