Sweet car, Jason. Here's mine.
Yours is the first I've seen the same color as mine. I need to get a set of stock wheels though. When I was prepping it for a track day, I put smaller tires on it, probably a little smaller than yours, to lower the overall effective gearing and gain some contact patch, and noticed the wire-basket wheels on it are HEAVY!
Do you know if the U-20 is at all rare these days? I believe it was also their truck engine, so perhaps not very rare. Still, I've considered taking out the U-20 and storing it and, what the heck, while I'm at it and do occasionally use it at track days, see what else I can stuff under the bonnet that's less valuable but more powerful. I was initially thinking about building an L20B for it, since I have a lot of experience with that one, but in snooping around the net for a posi diff for it (or, dare I hope, a posi IRS rear that fits right under it?) I ran across a lot of references to later and larger motors being bolt-in replacements for the U20.
Thoughts?
Introductory post about mine, followed by several others, including pics: http://cars.talkzilla.com/boards/read_msg.aspx?message_id=830