Carbon post in 531 frame....certain rules or just no?

The BIG GT

I need a (cheap) 'new' post for my old Raleigh 531 Reynolds framed road bike and am looking at eBay, etc.

There seems to be a surfeit of 2nd-hand carbon posts judging by the prices.

Is this because they are dangerous?
Can they be used in a steel frame (it has an allen key clamp, not QR)?
Are there any rules that must be followed for it to work?
Or should you never put carbon posts in a steel frame?

It takes a 27.2mm post and I am well over 14 stone.....if that is important!

Thanks.
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Monty Dog

Make sure the inside of the seattube is clean and that the edges of the seatclamp and free from burrs - may be worth getting a small file in there to clean off any sharp corners that could scratch your post. Get some wet'n'dry and give the inside of the tube a good clean and then wipe with solvent to clean off any debris. Put some anti-sieze on the post prior to insertion and check the post regularly to make sure it still moves and has some sort of anti-sieze. There's no reason why a post shouldln't last many years.