To do this subframe modification correctly you should obtain a copy of the No Limit Engineering video which shows how to do this. I believe it is about $35 and well worth the cost.
The camaro subframe to the task force series trucks 55-59 is a common swap. The G body swap is also possible but you will have more fabrication to do to solve clearance problems with the steering box and header clearance. The F body (camaro) is a better option for a subframe for your truck.