LS,LQ engine/tranny swap 51 1/2 ton short bed

[R&B51]

First time posting and new to membership. Have been viewing as a guest for some time and really appreciate all you guys do to help each other build great trucks. My college age son and I am just starting our first project together. Really nice original truck. Plan is to pull the clean original solid running drive train and do an LS3 or LQ4/4L80e type swap. A little overwhelmed by this process. Maybe the first question I have is how these things drive with a modern PowerPlant like this? Seems like we always are fighting for more horsepower and I'm not sure of what Will get a really strong fun truck to drive that we can still control. Probably expecting to end up in the 350 to 425 hp range with an automatic transmission behind it. TCI coil over suspension swap have already cut the old one off and removing rivets right now. Before we do this, maybe some input from you guys about how these trucks drive. Is this horsepower range reasonable for a truck of this weight I don't want him to get in trouble with it. Will have four wheel disc and better handling but still don't want him driving a beast that he can't control. Then, is there a market for this drivetrain and I'm pulling out? School me if I'm not posting right.