I'm still learning FPGA:s myself, so I'm not sure if I can give you a relevant figure. Currently the A1 pipeline (no memory subsystem) synthesises to 2000-3000 ALMs (or about 15% of the logic in the device I'm targeting). That will increase as I implement more instructions (the FPU in particular), but on the other hand it will probably decrease when I switch to using BRAM for the scalar register file.