Here is what I just posted in a current converter thread -
Many of the street/strip builds I have done lately have used 67 to 70mm turbos.
I have found that if we do not have a converter that will stall a minimum of 3100 RPM at 0 boost, it will be a laggy dog, even if it is a BB center section!
Depends on what 3500 and what it stalls to at full power. To put it simply I've yet to see a converter under $850 that can couple the power a turbo like that could produce.