Sounds awesome Horlock! In spite of being a bit of a sustained climber I do love everything linked to the classics and really fancy doing one of these sportives next year.
Kind of linked/shoehorned in here - I've got a weekend in Bormio in May where we will be watching two ascents of the Stelvio, as well as riding the route(s)
PS - I'm writing this from Mallorca on a cycling holiday
I would recommend the Flanders one, its only c.£30 and you get loads of stuff, its well organised inc timing chips and a live feed for others to follow on the web, feed stations were great etc. We did the 141km one which misses out the flat run in at the start that the pro's do but included all the cobbles and climbs.
Good luck on the Stelvio, would possible like to try one of the longer alpine climbs, although would probably have to be the Ventoux in the first place?
Now onto the ride to the sun in July, http://www.ridetothesun.co.uk/
we are not doing it on the official date as its fathers day the day after and thus is too politically sensitive, but following the same route a couple of weeks afterwards. should be OK, but no doubt bloody painful again.