It would have to be a GST or Spyder. The 420A mounts are way off. The 4G64 is similar in the block setup as the 4G63 even though it is a single cam. The are a few differences but you can use that block for a 4G63 head with some minor modifications. You would be left with a stroker motor in the end. The 64 has a longer stroke than the 63. But, your best bet is the 64 in the spyder, and use the 63 head.