>The downside of 68040 is all the memory needs to be 32 bit wide

I wonder if there's a way to make a board with 32-bit DRAM but no ROM. For example have a microcontroller on the board that holds the 040 in reset, loads the boot program into DRAM, then releases the 040 from reset. Same micro could potentially act as an I/O coprocessor using DMA to transfer data from network/storage direct into DRAM.