Need Help choosing a transmission

[bzblaine]

I have a 1970 C10 SWB. I'm trying to decide what tranny to put behind my 468 BBC. We are thinking it will be right around 550 HP/TQ. I currently have a TH400 for it. The problem is this will be a daily driven/ 3 days a week truck. I don't really ever plan on taking it to the track. My concern is that there is no overdrive. I'm not concerned about MPG. I'm worried about the health of my engine as I assume it would be running high RPMS at 75-80 MPH. I am aware of the Gear Vendors or a 4L80E. The problem is budget, I simply cant afford Gear Vendors right now and the 80E is computer controlled. I have about $1000 to spend plus whatever I get for my TH400. I also heard the 700R4 can handle right around that kind of power if built for it. I'm still in the learning process, so my apologies for my lack of knowledge. Any Ideas would be much appreciated. Let me know if you have any questions. Thanks!