The 302 is the holy grail of engines in their era. It was highly desired for racing engines for years. Even stock one would power your Suburban nicely.
When you find one it will most likely be from a big truck. The bell housing, flywheel and clutch won't fit in a smaller truck. Nor will the oil pan. The parts from a 1-ton or smaller with a 228, 248 or 270 will fit. You don't say what year Suburban so be aware the bell housing mounts changed in 1954.
There are civilian and military blocks. The military one takes some modification. There is info on that at
oldGMCtrucks.com. You'll need to sign up read the discussion forums.
