Looking for 8080/Z80 BASIC

Anyone have any recommendations for a reasonably featured 8080 or Z80 BASIC? What I've got running at the moment is a mongrel IMSAI 8080 with a Z80, 48K of working memory and a serial port. My eventual goal is to get CP/M running on it (I have a Cromemco 64FDC -- anyone know of either an official CP/M for this or know of a BIOS that supports this controller before I start writing my own?) but for the time being I thought it would be fun to get a BASIC running on it. The catch is I need something I can adapt to the serial I/O on the Cromemco controller -- so something that I can pretty easily modify is of course preferable. (I'm not opposed to manually hacking up a binary but having an official source listing to start with would save time :)) I started looking at the IMSAI 8K basic listing but there's a fair amount of hardware-specific I/O code in it scattered throughout so I'm not thrilled about modifying it... (and the only source listing I can find is in a PDF, which doesn't help any...)