1.) Call/e-mail Accurate Power and buy one of their 62mm butterfly's. also get their measurement for the TB's they do.
2.) find a local machine shop (preferably an industrial one - they're cheaper) and have them bore YOUR'S out the correct measurement.
for about $75 grand total you can have a 62mm tb - not $250-$300.
p.s. if you go to www.car-parts.com
and find one from a junk yard (i found 1 for $50 including shipping) and have that one machined. then you don't have to have your vehicle down. if you like it you can machine the other one down and sell it off for some profit.