These are your Grandads' trucks? And you're going to whack them up? Mistake of a lifetime.
They might be clapped out junk lying behind the barn but they are family junk that deserves respect. You can purchase something to 'have at' and make mistakes on - reread rfs56trk - learn and when you have enough skill then pick one of those trucks to build.
Imagine the pride of driving a cool '47 in 2047 and it being your Grandads' truck, you only get that oppertunity once in your life.
While I understand where you are coming from with your opinion about don't "whack them up" and "they are family junk that deserves respect", I also see another side to that sentiment.
The truck I just started working on was purchased new by my Dad in 1953 and it has been in my family ever since. There was a time when I was thinking that I could not possibly do anything to the truck except restore it to like new out of respect for my Dad. But then I thought about projects I had worked on with my Dad and other vehicles I had seen him work on...and I realized that my Dad was never against changing, improving, modernizing a vehicle for the sake of making it into something he wanted it to be. If he were here, I have no doubt he would be working side by side with me to make the old truck into what I want it to be, so I can drive it and enjoy it just as he did in his time.
My point is, without knowing the OP's grandfather and family, we cannot say if doing a hi performance resto-mod is respectful or disrespectful.
To me personally, disrespect would be to allow the trucks to rust away, saving them to ride again, in any form, is a good thing.
Just my .02
Tim