in the same postion as you with t34/63. there has just been a TT T38 on ebay went for £665. have spoke to several people about it a suitable upgrade and if you want a direct replacement without changing stuff like wastegates ive found the following (but there will be others)

gt30 from AET turbos (recommended by mark shead)
gt30 from karl norris
T38 from mike rainbird
T38 from turbo technics and others

dont know which one to go for in terms of lag and spool up etc.