Possible engine crack in the future?

So a new friend of mine I met at a local monthly bike night was admiring my '82 of the same bike, I mentioned I'd done nearly all the restoration work myself. They said they laid their '83 KZ750 LTD down at about 10-15mph on a left turn on slick, wet pavement.

They want me to do the repairs, and while I've pretty much finished it save for the spedometer, which I have one coming in the mail, there's one question looming over the bike...

Another friend had a Rebel 250 that they rear ended somebody with at 5mph. The only damage I could find was the after market windshield and the forks, which I replaced. I told them they need new tires because the tread was past due for a replacement. They bought new tires and on the way to a garage to have them changed, the cylinder head cracked right at the carb intake point.

The mechanic at that shop said it's a common crack on Rebels and most certainly wasn't related to the accident. That said, I can't be too sure... The mechanic who said that is a guy who, while I highly respect him, he's been known to be wrong about things, even on bikes he's supposedly an expert on (like KZs).

So that's what I'm worried about. There's some minor scuffing on the side of the engine which I've outlined in red here:



So the bike went down at a modest speed and dragged a few feet probably. My concern is that the impact may cause an engine crack in the future, but I'd like to get a second opinion on this before I turn the bike back over to my friend and say "everything's good". The mounts seem good. and nothing else seems damaged.

I figure leverage wise, it probably didn't impact all that hard, afterall my friend's hand, he said was just bruised when the handle bar slammed it into the pavement, and the green internal plastic housing on the spedometer was merely minorly cracked from it. It still worries me though.

Based on the picture I would think motor damage highly unlikely .
Check the inside electronics when replacing the cover for damage
But other than that , Not likely
Dave

I wouldn't worry about it.