The pcmcia driver was updated for these kernel to eliminate the need for the config.opts mangling. The new driver allocates the entire 64k for shared ram and it needs to be aligned on a 64k boundary, if you've got a previous srambase value not on a 64k boundary, the driver will barf and the kernel will panic. Use the built-in kernel pcmcia driver and play with config.opts. If you want to use the latest and greatest version of the driver with the high memory and hot-swap support you can download the patch and patch up your kernel. Then the line in config.opts can be removed and everything will work fine.
Official support is for the drivers in the kernels available from the official kernel mirrors.
No set of values is guaranteed to work the same on a different machine. It really is a case of trial and error but forewarned and forearmed with a little bit of knowledge can make the process a whole lot easier. Hey, I don't care, just give me something that works OK, try this, it works in most situations, if it doesn't you have to read the rest of the section anyway. Theoretically you should be able to use anywhere within this area, although experience has shown that most machines hide stuff in the 0xc0000-0xc9fff area. So you really want to stick with memory allocations in the 0xcc000 - 0xdffff range.