unless your car is emensly modified and crafted from at least 200kilo's of wag and filler, then there isn't much point trying to bodge a twin cam head to a 1.1, the block on teh 1.1 is too small for a startoff for the 1242 16 head to fit
if you want a fairly easy engine upgrade, then plumb a 75 and associated gear in there, (it made a fair differenece to my 60 having 75 gear in there).
next stage up is the 85/ 1.2 16vsporting engien (also comes in cars with a 85 badge)
then the 1.6 8v, this is a dog of an engine, its heavy, drives like **** compared to its sucessor, and pretty much untunable without 5k thrown its way, for which money you could buy a whole 5m of decent car.
then the 1.4 8v turbo, which is possible, but you are basically going to have to strip the interior and whole front end down to subframe and beyond to do this, to fit mechanicals and electrical componants.
sorry to say it, but if you want a 16v head fitted to the 1.4 8v you are wasting your time, ask anyone on puntosports.co.uk who will tell you about how good the 8v is as it stands.
all that lot probably sounds confusing, so to sum up.
option 1) 1242 16v from a sporting/85, into whatever car you have inc lots of wiring (that means dashboard out again matey!), I think the gearbox is different too.
2) buy a sporting, and fit your goodies
3) buy a gt, and fit your goodies
they really are so cheap that its a more financially viable option, even if doing the work yourself