I just received an IBM 5170 AT-class 286 PC!
Retro PC's have become my hobby and I'm pretty fluent in everything 386-present but this 5170 is pushing my horizons a bit, so I could use a little advice.

My 5170 has 512KB base memory onboard - and that's it. The seller also included a loose "Maximizer AT" 16-bit ISA RAM card with original manual. I've been able to configure this card to fill out the base memory to 640KB, and add an additional 1MB of what the manual calls "expansion memory." Man, expanded memory versus extended memory, high memory, upper memory, ugh! It's hard to keep it straight.

Here's the output from the mem command in DOS 6.22 with himem.sys loaded, showing what I have now:
Memory Type..........Total....Used.......Free
---------------- ------- ---------
Conventional..........640K......17K.....623K
Upper..........................0K....... 0K.........0K
Reserved..................384K...384K.........0K
Extended (XMS)....1,024K.....64K....960K
---------------- ------- ---------
Total memory.......2,048K...465K..1,583K
Total under 1 MB.....640K.......17K....623K
Largest executable program size......623K
Largest free upper memory block.........0K
MS-DOS is resident in the high memory area.

My next goal is to get Windows 3.1 running on this machine. I know I don't absolutely need it but I'd love to have 4MB of memory available for that, but the Maximizer AT card only supports up to 1.5MB after filling out the base memory. That last 512KB is populated on the board btw, but I get parity errors when I enable it. I've moved chips around and the error still always points to the same location so I've settled on this being just a 1MB card. So the next step is I need to choose another ISA memory card, but I need advice/help choosing. I'd prefer to get something period-correct, although I do understand there are some modern "Lo-Tech" 8-bit cards with 1MB or 2MB - but I'm having a tough time figuring out whether they'd even provide the "right type" of memory for my use-case. I'm also assuming there would be a performance bottleneck versus a 16-bit ISA card.

I'd like to get something like this:
#1 https://www.ebay.com/itm/254530549818 "JE1084 board"
or this:
#2 https://www.ebay.com/itm/184359737433 "BocaRam AT"
or even this:
#3 https://www.ebay.com/itm/324372089575 "BocaRam BRAT90"

The first one looks like it would be easy to work with because it uses SIMMs and could give me all the RAM I'd ever want. It appears to be configured by switches - but I cannot find ANY documentation for it (how to set the switches).
Number two looks to have 1.5MB RAM installed, and it's the only one I've actually found documentation for so far, but it's not a sure-thing because the terms of sale are such that I'm stuck with it if it arrives dead. The others aren't like that.
Number three should work IF I could find the software required to configure it, but so far I haven't been able to find it.

I'm fine with other suggestions, or even a modern product if there's something available that will definitely work for my scenario. Any thoughts??