That link to Kirkn's post was great hoodellyhoo, I like replies like that to questions us newbies ask that have been asked a million times before, thanks.
I did this about 2 months ago without the cooking and freezing, just a trusty blow torch and everything came out the same. I also had the problem of the top being a hair higher but as I'm using different headlight mounts, I don't think this will be a problem. The only thing not mentioned so far and maybe it's just me, but the lower dust seal was somewhat tricky to get in as you need to make sure the lip on the seal doesn't turn over, nothing a little patience won't cure. I will be removing the top dust seal though just to see what effect this has on my setup.