Turbo Explanation, Please Help Explain.

[240sx AutoXer]

I am not sure if I am posting this in the right thread, or if this should go in Engineering as I am looking to try and gain knowledge about turbos specifications.I just recently blew up my stock RedTop turbo, so I want to upgrade while replacing.First a little about my car: Started with RedTop SR20DET.Factory S13 Turbo with Internal WastegateBlitz Blow Off Valve (Recirculated)Brian Crower Balanced Stroker Kit 86.5mm Bore 9:1 RatioBrian Crower Stage 3 CamsBrian Crower Springs and Titanium RetainersGreddy Rocker Arm StoppersARP Head StudsARP Main StudsARP Rod BoltsACL Race Main BearingsACL Race Rod BearingsACL Race Thrust BearingsNissan Red Top HeadExtrude Honed HeadNISMO Metal Head Gasket .5mm 87 BoreFreddy Intake Manifold (Smoothed Runners/Port Matched)Machine Shop 3 Angle Valve JobNissan Stock ValvesRC Engineering 750cc Top Feed Injectors SH4-750D Sat.SARD Fuel Rail Top Feed ConversionSARD Fuel Pressure Regulator Type-RJWalburo 255 Fuel PumpAEM 30-1601 ECUGreddy PRofec B-SpecII Boost ControllerRoyal Purple XRP 5W-20 Racing OilRoyal Purple “Purple Ice” Coolant AdditiveNGK Iridium Spark Plugs 23 gapDynaPack rated at 250HP at 14psi at the hub.

I use the car for autocross and track days, but no drag racing. I need quick spool with decent top end. Looking to get up to 500hp or there about.

My question is what do the T: 53.85mm-76trim / 64/86 A/R, C: 71mm-52trim / 60 A/R values mean and what values should I be looking for in a replacement.

One last thing to consider is I will be retaining the power steering and the reservoir which limits my options for fitting different Turbos.

Any help from fellow SR20DET owners would be greatly appreciated.