BEWARE: I have not tested this but, it is so simple and I can see no reason for it not to work.
If you have already installed this 32K console SRAM mod, then it won't take much more work to fully populate the RAM space at >8000 to >83FF. That would give you 1024 bytes instead of just 256. It seems to me that disconnecting the CS* from the 6810s and moving that signal over to pin 4 of U504 C2 (first remove the +5VDC from it) should be all that is necessary. I see two possibilities for doing this.
I think this might be the easier of the two but, you may find other possibilities that I didn't consider. The signal could be removed from the 6810s by cutting the trace coming from pin 8 of U507. Run a jumper from pin 8 of U507 to pin 4 of U504 C2. Do not forget to remove the 5VDC from pin 4 prior to connecting this jumper, though. Cutting this trace at this point cuts off the connection to U606, pin 12. In all likelihood, you would want to reestablish the connection from U507, pin 8 to pin 12 of U606. This would be required, if you have the defeat switch installed, so the Scratch Pad memory would still be fast memory when the switch is in bypass mode.
The 2nd solution I came up with was to pull or cut the CS* pin on BOTH 6810s. Then run a jumper from the hole that is left under pin 11 to U504 C2-4 (again, remove the 5VDC from it first). This doesn't break the connection to pin 12, U606, so nothing more should have to be done. Alternatively, you could remove both 6810s from the board since they will not be used anymore. I intend to leave them in, possibly to be used as a small buffer for another idea with which I have been toying.
I made up schematics for what I call the Clulow-Guion 32K upgrade, and I am attaching them to this post. They are intended as an addendum to "Hardware Manual for the Texas Instruments 99/4A Home Computer" by Michael L. Bunyard. The largest difference between the CG32K and the BC32K is the CG32K can be switched back and forth between 0 wait states and the normal 4 wait states using a toggle switch. I don't think you can hot swap it, though I can't offer first hand test results. Even though I am going to use this as a basis for the 1st stage of my own design, I do not intend to use a toggle switch to bypass the zero wait state in mine, so chances are that I never will test a hot swap of this particular mod. I want to be able to hot swap mine via software, and perhaps a mechanical push button. Instructions for the three current Ballmann-based mods are found here: http://www.mainbyte....32kconsole.html
Please let me know if you think I'm in error with the schematics or the modification I've suggested. If you try it and it works, please let me know. If it doesn't work... well, that's your fault for trusting me.