I want to know if the cylinder head from either a (1990's) Peugeot 306 or 405 1903cc engine will fit the 1759cc Peugeot 205 ? My 205 has a cracked head and I have 405 & 306 heads only available.

check where the valves on the head are situated.If the valves are flat then its ok as long as you use the thick washer on the 405 head

Interesting dude, presume you have 205 one off?will have to come off regardless,look for part no,s to compare or put the 306 and 405 ones beside it and compare to make sure, would say the 205 and 405 would be the same, but CHECK, dont take anybodys word for it, been up that road, can be expensive, not to mention the inconvenience, best of luck man;

YES the 306 head definetly fits with no bother, not sure about the other one tho.