That's very basic. I would think you would want coolant temp as well, and battery voltage correction. You'll find it difficult to get the car up and running without coolant temp correction. There's no idla air controller? You can implement simple anti-slip if you interface a VSS sensor. Knock sensor?
Unless the O2 sensor is a UEGO or a wideband sensor it'll be useless for a racecar. Standard sensors can only accurately sense 14.7:1 stoich, and you don't want to be running that lean in a racecar. Are you trying to do closed loop with a UEGO sensor, then?
What resolution do you want to shoot for with the fuel/ignition maps, and the correction maps? Remember, once you add up all the correction maps, for fuel, and then for ignition correction, you're getting into large number of lookup tables and alot of data. It's unlikely you'll be able to fit all that into the 4k of RAM your limited to on most of the 8bits so that you can do real time changes.
To add to your sensors, I assume you're taking it for granted, but you want it to read the crank angle and crank position (sync) sensors as well. You can leave out sync if you're not doing sequential. Are you trying for batch, or simply multipoint? Direct fire ignition or do you have a distributor?
You also have to decide on the outputs you want. Tacho, speedo, engine warning.
You're probably better off looking through all the diy-efi archives.
I have a DIY kit, which unfortunately is not available any more:
http://www.efikits.com for my ems, but I have a dash display and datalogger I'm working on myself.