A reasonable question, under the circumstances. Might the answer be to accrue some engine run-time and to commence the process of 'learning to fly' the a/c on a step-by-step basis? Apparently it was also a lot of fun, and the rebuild crew might have been justified in rewarding themselves. High-speed taxi next... presumably with the pitot tubes uncovered?
That's what you do when testing a new aircraft or after major overhaul or an accident. Step by step to prove everything works ok. You can't pull over to the side of the road if something goes wrong in the air.
