re: "...a 86 240 that has a slipped timing belt. I have a friend that has rebuilt a B230f engine and he said there piston/valve contact is this true?..."

Despite what your friend says, it is not an interference engine. Valves and pistons cannot meet. When the timing belt fails, the engine just slows to a halt without damage.

Later engines, past the era of the 240, are different, and are interference type.

The one exception for these B230 engines that I've heard about is a 16 valve (4 valves/cylinder) that I think is called the B234, and was in a 740 or 760 with a special 16 valve badge on the trunklid -- this was an interference engine. If I'm not mistaken (it's been many years), I think it put out approximately (give or take 10 hp) the same as its contemporary turbo version of the 8-valve.

And, of course, if the engine was heavily modified with high compression pistons and a shaved deck and head, it is conceivable that the valves and pistons could get close enough to clash, but that would be an extreme case.