MGAs are definately cool, and a tad on the more rare side. I would have a hard time doing a custom/resto thing like that on a hard core classic such as the A.
On the other hand, MGBs cna be had a dime a dozen, while the BGTs are bit more rare, its still a MGB and not as worthy.
I work for
www.victoriabritish.com,(catalogs are free)we sell resto parts for both cars you just mentioned and a dozen other British roadsters from Triumphs to the classic Austin Healy.
Pick up this Oldsmobile IRL engine on eBay, throw that biatch in a MGBGT with a custom interior and you got a definate showstopper!