Hello,
AFAIK There isn't any kits which use a single 72pin simm or 4 30pin simms. The only kit I know of is the Marpet kit which used a whole bunch of RAM IC's. The cost of this kit was HUGE though it did offer a plugin option. IMO from what I have read in the past people have had nothing but problems with the plugin one. The solder-in kit by them should work fine though.
I'm working on the 72pin board as you know at the moment. I keep changing the PCB design trying to find the best place to fit it all. Due to the stupid amount of PCB revisions and other things I won't be producing a plugin board, at least I doubt it anyway. The new design is only half built so far. If there is a lot of interest then I will try to finish the design quicker.