The 8" Toyota rear end is pretty strong. You will need custom front and rear driveshafts, as well as a custom (or modify the stock) tcase crossmember. With the SBC you will have to notch the firewall as the distributor is on the back. Being as yours is a IFS you will need around 4" of suspension lift, or a custom oil pan to clear the IFS differential (With a SBF a dual sump pan and a set of 1" spacers on the motor mounts with clear). Stock manifolds will clear on either, but swap headers make it easier. A body lift makes the entire swap easier. Other than that its basically as straight forward as any engine swap.