It appears the two pieces (the tube and the piece that broke off) fit together tightly, so I don't think any other bits of plastic made its way into the crankcase.
For the remaining five tubes, I used the 1" transom plug method I got off another forum. Picked one up at Bass Pro for $6. Works great! Pelican should start stocking these.
The car has been a blast to drive. I've been thumbing through your book. Already planning another big project. Thinking of upgrading to the ROW M030 suspension as a DIY. Will be looking to Project 63 when I do.