i've heard of people who have modified a small turbo cover on to a big turbo head, it needed welding & re-drilling, therefore i should imagine you could do it the other way round!
if it wasme i'd get a secondhand small turbo cover, no mesing about & all genrally prefer the look of them.
give Paul at 'north yorks rs breakers' a call, he'll probably have one.
(rember the gasket is also different)