Master Power doesn't make Turbos for the US anymore, but you can get Magnum T70's which are basically MP clones, only probably a little better and you can get them in ball bearing too. A T70 on a 5.3 is a great fit. 43's won't get the job done with E85, your gonna need 60's and a good fuel system. With the right tuning and about 10-11 psi, 500rwhp should be do able.