XH series 2 couple of questions

Hey everyone,
firstly, great forum, ive always stalked it but only just now signed up.
always one of the first places I go for info.
basically ive always wanted an xh, time has finally come to get me one.
To start of with I will being chasing power gains and I am aiming for 300rwkw.
My questions are:
Which engine has the potential to get to 300rwkw the cheapest? (5l xr8, 4l i6 xr6 with turbo or swap an au series in and turbo)
Basically im looking for a push in the right direction from the experienced guys of this forum.
I understand there will be a substantial cost involved with any of the options but this is going to be my project car
and I will be keeping it in definitely.
Thanks in advance for any info.
P.s
I can do most of the work myself and plan on building this from the ground up.
firstly, great forum, ive always stalked it but only just now signed up.
always one of the first places I go for info.
basically ive always wanted an xh, time has finally come to get me one.
To start of with I will being chasing power gains and I am aiming for 300rwkw.
My questions are:
Which engine has the potential to get to 300rwkw the cheapest? (5l xr8, 4l i6 xr6 with turbo or swap an au series in and turbo)
Basically im looking for a push in the right direction from the experienced guys of this forum.
I understand there will be a substantial cost involved with any of the options but this is going to be my project car
and I will be keeping it in definitely.
Thanks in advance for any info.
P.s
I can do most of the work myself and plan on building this from the ground up.