Hi, I planning to buy a bombridge 27 but there is rust on the keel plates/bolts. Should I be worried?
worth buying it?

I'm guessing you can not post photos yet but a link to the ad might help!

maybe hallettboatbrokers.com.au/boat/280901/bonbridge-27/ ?

That one has SOLD in the text so assume not.

Would certainly be worried. For the expected age (late 70s-early 80s) it would be very difficult to determine the extent of the rusting of the keel bolts and cast iron keel at the bolts / keel interfaces. You have probably seen the below links?

marskeel.com/your-guide-to-keel-maintenance/#:~:text=Corrosion%20of%20the%20keel%20bolts,both%20lead%20and%20iron%20keels.

www.cruisersforum.com/forums/f55/keel-bolts-in-cast-iron-keels-290556.html

www.sailnet.com/threads/rusty-keel-bolts-how-bad-is-it.67272/