So like 301 ? 350 ? 450 ? 550 ?
GT30 of any kind is a poor choice for only 300hp ( although a T34 isnt exactly great either )
There are just better more modern alternatives, and choice will depend on budget. Whether BW EFR, Precision or some of the newer GTX Garrett's, probably in GT25 format
At the cheap end there are some good oil journal BW's too. Although most may require some fab work.