Rickster, when in doubt, have your block sonic tested. If you do any performance driving, do NOT use a block that has anything less that .125 (1/8th inch) wall thickness.
If you still have doubts, talk to those who know the limits best, past national record holders, Aldon Miller Idaho, Richey Pauley California, Jim Waldo, Washington. .125 for street or strip is the rule of thumb.
Good luck
GT-347
www.forddragteam.com