The option of using an existing plate is one that I have available, as I have a plate. I've been wondering how I could use it as a template for drilling the plate that is attached to the engine. I'm thinking that I could clamp the extra plate to the one that needs drilling and go from there. However, I am guessing that I'll need to either lift the engine and go from below or lay it on its side and go that way. I think that there are pros and cons to either approach, I just haven't slogged through them all in my mind.
I agree with you about the nagging feeling about the salvage engine (which mine is). However, I just don't have the money right now to do a rebuild. It's either chunk it into the truck and see if it's driveable or wait a couple years saving up the cash. Seems like a no brainer for me. I want to drive the truck. So I'll live with that feeling. Assuming that I can get through all the rabbit holes and get to the point of actually doing the transplant.