Ian,
you do not need a 60 MM wastegate. A 38 MM wastegate will work fine for you. 38, 40, 44MM will work. You do not want to go too big though.
Here is a nice one. http://www.ebay.com/itm/Tial-38MM-wasteg...4d33641&vxp=mtr

http://www.bing.com/shopping/tial-sport-...RM=EGCA&lppc=16

My Syclone has an internal wastegate that has a 27 mm or 1 inch hole & it works OK for me & I run as high as 25 PSI.

I do not recommend you using a 27MM wastegate, just saying that what I am currently stuck with.

MBHD

12 port SDS EFI