If it had bent valves, you'd know it. It wouldn't run smooth at all. If it really is an interference engine, I don't know how you escaped without damage. I'd have him do a compression check on it just to make sure.
If it happens that the engine is damaged, and you don't have a source for another motor (It'd probably be cheaper to replace than repair) there's a GreenLeaf Auto Recyclers down here. Low mileage engines, and they will guarantee them. I can transport it from here to your place if needed. Call John Marsden at 800-942-7278, ext. 5080, 770-207-5080 or his cell at 706-247-6060.