The DSI Modular Mac sounded like the ticket right up until you said "full-size". There are numpad modules, but that still doesn't change the fact that the Ins/Fwd Del/Home/End/Page Up/Page Down and arrow key clusters are rather scrunched up against the alphanumeric portion, and Home and End are actually Fn + Left Arrow and Fn + Right Arrow, respectively. There's also no gaps separating the function keys, which will screw you over if you're used to feeling around those gaps to find the keys without looking.
Aside from that, if the Matias Tactile Pro line isn't your cup of tea, it looks like you'll have to get used to having Cmd and Opt/Alt swapped. Sure, you could do so in System Preferences, but if you need to hold those keys down during a cold boot for whatever reason (say, selecting which OS to boot from)...