I installed the Thunderbolt engine and standard prop. I found that I needed a little weight (~10 lbs) in the baggage compartment during phase 1 (minimal interior, no paint) to stay well inside the CG. Perhaps, consider leaving the ELT where it is until painting etc. is complete.
The airplane is now out of phase 1 and in the paint shop. I will be weighing again after paint and can evaluate.