i had a 96 gt and it was a dog. i was researching the head swap when i realized how expensive mod motor stuff is. to do the swap right (ported heads, cams, long tubes, ...), it would have cost about $3000, and then i would have been at probably 280-290 hp. not worth it imo.
that was when i decided to sell it and buy a 94/95. i bought this car for $7000, $1000 less than i sold the 96 for. a h/c/i costs much less (and you have lots of kits to choose from) than the pi headswap and you net more hp. plus i can go to a 347 easily. and the blower i have on it only cost $2500.
dollar for dollar, i have gotten alot more out of this 95 than i would have for the 96. i have no regrets at all.
94/95 cobras are not nearly as plentiful as the gt's are. if you find one in your price range, i would say go for it. otherwise, you can just as easily take the money you save by getting a gt and put it into upgrades.
if i had $10K, i'd look for a 94/95 gt that doesn't need body work or paint and try to get it for like $5K or $6K. then i'd put the rest into upgrades (H/C/I, exhaust, tuning, wheels, brakes,
suspension, new seats, ...) i'd probably run out of money before doing it all, but that would be my approach.