Prince danger
If you are aiming for 500hp i would rather go for the GT3076 double ball bearing. you can use a .63 housing or a .82.
.63 with some water injection can allmost muster 500hp and will be 20 or 30hp short. The .82 will exceed 500 hp.
However if you want to produce more than 550hp i would then go for a turbonetics cause of the thick shaft and strenght.
The Garret will spool faster than the turbonetics.
I currently run a GT3076 with a .63 housing with 7.5 comp bd 16 inlet bd 15 exh camms with a Rs 500 intercooler and at 5500 feet above sea level i have 0.5 bar at 2800rpm and full boost of up to 2 bar at 3900 rpm
Please bear in mind that at this altitude we have 300-400 rpm delay in spool up.
The .82 housing will give more lag but more hp.
There is a 1.06 housing rated at 565 hp too.
Make shure Julian gives you 8.5 comp pistons. It aids the spoolup and hp.
He runs it on his setup