I would of rather fixed the problem with the trans. On your 200-4R, the governor is what controls the shift points. I'm not sure if anyone makes governor kits for the 200-4R now, but you can try this> The governor will have two weights on it. Tack weld a really small nut on each of the weights. This will make the trans shift sooner. If you remove material, the trans will shift later. I use to remove material when I had people swapping in a 200-4R from a grocery getter into their street machine. Same goes for people with the Buick T-types, GN's, Etc. when they blew their trans up. They would get a donor from a grocery getter and be disappointed with the way it shifted and performed due to the early light shifts.
Also, NEVER use your throttle cable adjustment as a way to mend a shift point problem. This will only force your trans into early retirement.
