I stumbled across an interesting web site recently about an EFI that does NOT control the ignition. You can use your stock distributor or anything else besides an MSD. For about $230 you get a kit that you assemble yourself, including a simulator for diagnostics and testing. However, it is up to you to find correct injectors, plumb them, and arrange the rest of the fuel system.
I need to do a LOT more research on this but it appears at first glance to be something neat I could put on my 261. Please post if you are familiar with this setup--good or bad. Go to the MegaSquirt website at
www.msefi.com.