[mr48chev]

I'm going to have to quit reading these things late at night.

If you are using engine and trans out of a donor rig (s) I'd suggest using an engine and trans that came out of the same donor and have the computer to match as part of the deal.

200R4 is good for a mild engine and light duty. 700R4 you can tow with and run more power with without special internals. Both don't need all of the computer controls that a 4L60e or 4l80e do. The E standing for electronic controlled.

I don't think you will have as many issues in a 57 truck or panel transmission clearance wise as you would in an AD.

My preference is having the crank and main shaft centerline of the New engine and trans on exactly the same line as the original engine and trans to the point of taking measurements before I pull the original engine and trans and set the replacements in place. Meaning that if you lay a straight edge across the frame rails with it right in front of the end of the crank and measure how far the center of the crank is up or down from that straight edge your replacement should match that measurement. I haven't seen it in TF trucks but have seen AD guys mount small blocks several inches too high and build big tunnels simply because they wanted the engine to show when you stood back fifteen feet.