Well, I guess I'm the king of stupid stuff on this forum. I think if I were gonna do this, I'd use a Cadillac Eldorado or Olds Toronado front-drive unit in the Monte. At least the TH425 and the diff would be strong enough to handle a pretty good load of hp. You might even change your mind about the SBC and decide to use a 500 cid Caddy with upgrades to the valvetrain.