The brackets will not fit, but could be modified very easily to fit the MGA shock mounting bolt pattern. The lower brackets should bolt on as they are.
That said, from what I've read over the years on a variety of MG related bulletin boards you would probably be happier in the end staying with the original lever action shocks. You still need them as a locator for the upper trunion, so you will always have the wear problems there. The main problem I've seen and also experienced in using tubular shock conversions is correct selection of a shock valve that will give the ride desired. Yes, adjustable shocks help in this area, but they are only adjustable in a given range, and in most cases the weight and travel of the MG winds up having the best setting at one end of the shocks adjustment, so no room for extra tuning.
I think you'll be happier in the long run with a good set of new or rebuilt shocks and perhaps uprated valves if you do some spiritied driving. You might check Barney Gaylord's web site, he's been autocrossing his MGA for years and recommends stock shocks highly.
http://mgaguru.com/
'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
"There is a fine line between a hobby and mental illness"