I'm running an older turbo (t3t4 60-1 garrett) what new BB turbo is equal to this?

 

somwthing between a GT30R and GT35R?

they are almost equal in flow but the BB turbo's may spool quicker and have better overall performance.

 

They can make a cartridge to fit that same combination, but it won't do a whole lot of good, due to the wheel design. Something similar to what you're looking for with the improved design from my experience was the GT3040R (aka GT3082R).