I have a 681f 6015 DA (tall block 1600) crossflow that is in pretty much standard condition eg chambered head, dished pistons....I also have a 711m "flat" head and (you've guessed it) I was wondering if the head could be swapped without much trouble and what the likely compression ratio increase would be. Cheers Mick.

Hi Mick,
I have a 681F block with a 711 flat head, I'm not sure how much it is going to increase your compression ratio by, you could pull the head off and CC the chamber and work it out.
 
Cheers,
Rick