The EFI inlets have a cutout in the ports that meet up with the head, for the injectors. If you use anything else you will have to cut those in, or get an adaptor plate for them. And you will need to find a way to mount the injectors because the fuel rail bolts to the EFI inlet.

Also the EFI inlets have electronics like a throttle position sensor, air temp, that you willl need to somehow make work on whatever other inlet you choose.