1. Marinate roast in sauce made from soy sauce, sherry or madeira, garlic, cinnamon and thyme for 2-3 hours, turning often (reserve marinade).
2. Place roast on rack in shallow roasting pan and roast at 325 degrees F for 30 minutes per pound or until internal temperature reaches 160 on meat thermometer.
3. Approx 20 minutes before roast is done, In a small sauce pan combine reserved marinade, peach preserves, chili sauce and 1/2 cup water. Bring to a boil, stirring constantly.
4. Baste pork with sauce and cook 10 more minutes.
5. After removing roast to rest, add remaining 1/2 cup water to roasting pan to scrape up brown bits. Add pan juices and water chestnuts to sauce and heat through.
6. Place carved roast on platter and spoon sauce over. Garnish with parsley.