Sure, it should work. I don't know of a Plus schematic published anywhere, so you'd have to trace the decoders and find the matching address line to a 128/512.
On my Mac 512K MoBo, the W1 jumper is between a pad connected to +5V (not ground) and an address line. The 47 Ohm resistor is between the output of the decoder chip and the jumper pad and should keep the decoder from burning out when its output is shorted. Grounding the pad will also disable it, but Apple tied it high.
Unless you're doing software compatibility checking, I can't see the point in disabling memory. You might as well block off memory with software, for instance create a RAM Disk that leaves 128K for the OS and apps. It's like taking 2 or 4 spark plugs out of a V8 so you can have a 6 or 4 cylinder car. It doesn't improve anything, it just cripples the car and makes it slow. 128K is too little RAM for a Mac. The original Mac which Steve unveiled at the stockholders' meeting had 512K. A 128K Mac couldn't run the demo. 128Ks were sold to the public because 512K was too expensive for the margins Scully insisted on. Unless you have a 128K museum piece, there's nothing special about that small RAM. I suppose running out of RAM is a novelty today, so it's fun to experience? :lol: