If this is your motherboard:
https://theretroweb.com/motherboards/s/bcm-fm540
You're looking for a COAST module (Cache On A Stick) for the CPU cache. There were two common variants, a 256k and a 512k module. I have seen mention of a 1 MB module, but never have seen one in the wild. The 512k module will make the machine perform a bit better than the 256k module. Also be warned, there were other "cache on a stick" solutions for 486 motherboards, which are NOT compatible and may damage your motherboard. UMC and PCChips were most common.
This module is probably what you need.
https://www.ebay.com/itm/275297390648
The 512k modules are harder to come by. I don't see any active listings from a brief ebay search.
As for the video memory, you just need SOJ-40 DRAM ICs. If you look up the memory chips next to the open sockets, just buy some of those and put them in the sockets. They're the same chip, just soldered to the board. Since those chips came in different capacities, I couldn't tell you what you have without seeing a part number. I did a quick search on ebay and found a bunch of listings for them. Make sure you buy the correct capacity chip. If you get the wrong capacity, you may have strange behavior from the video chip, like screen corruption on boot.
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That board apparently takes up to a Pentium 133. It's probably also possible to use an interposer, like an Evergreen Spectra 400 and get up to an AMD K6/2 400 in it, albeit with a 66 MHz bus speed. It will perform worse than on a native 100 MHz FSB, but still much better than a Pentium 100/133.