That was one of only three Shadows we built with destroked big blocks originally. I never liked the balance in those hulls. My suggestion would be to re-power with either small blocks or Ilmors.... and be prepared to use extended drive shafts for engine positioning.
You could also put brackets on it and run with OB's........
If it has been outdoors for 4 years bring a water gauge to test the hull.
T2x