The SE, Plus, and Classic are all more similar to each other than any of them is to the Portable. (I just looked, coincidentally there's a comparison of the Portable's and SE's memory maps in the Portable's developer notes. This:
http://support.apple.com/kb/TA46747?viewlocale=en_US
Says the SE's and Classic's memory maps are identical, and there's extensive docs of the Plus floating around, which again, matches the SE's quite closely.) Therefore:
If *any* part of this card's hardware or the driver software does any physical address translation to map the motherboard's peripherals into the 68030's bus it'll screech and die when it finds that the base of ROM is 5MB higher than it's "supposed to be". (Not to mention all the peripherals are in the wrong place, which could be a big deal if the driver for the accelerator applies any ROM/OS patches to paper over the speed differences. Certain peripherals in the Mac, such as the floppy controller, are very processor speed dependant.) At the very least I smell the need for a new version of the Init software.
In a number of respects the Portable can be thought of as being a strange hybrid between the Monochrome Macs and a Mac II. I just don't see "shove it in and see if it works" as being a good strategy here.
Another minor point is the Mac Portable is all CMOS, whilst I *believe* all the desktop Macs listed were still using TTL-level circuitry. The developer note doesn't mention difference in voltage levels, but there's a non-trivial possibility that even if the clock speed differences aren't a problem (and I wouldn't underestimate the chances of that) if there's TTL circuity on that card it may not reliably drive the portable's bus.
Anyway, good luck. Hope you don't end up killing anything.