If you want a "paper annual", you can find someone, somewhere to sign off for you - Labor = $0, pen = $500.
If you follow 14 CFR 43 Appendix D requirements, you will probably require 15 - 20 man hours (C-180/182/185) to do it properly.
You may be able to do this in less time if the A/C has been operated as per the POH, has a good maintenance history and it's logbooks are familiar to you, work is done as a team and tools/resources are easily accessible?
In the late 80's, I put together seaplane/ski-plane programs for the US Coast Guard and US Customs.
This included everything from acquisition, operations, parts inventory, maintenance, training, disposal...
Today, you can go to the Department of Interior's web site and see some of that work.
https://www.doi.gov/sites/doi.gov/files ... _tr_03.pdfGovernment operated aircraft are maintained to a higher standard.
Government pilots are also held to a higher standard.
However, Government pilots and mechanics are humans and humans make errors.
Every Continental Engine came with Instructions for Continued Airworthiness (ICA). Engine preservation and storage instructions are in Chapter 9 of this manual and clearly define storage and return to service instructions.
Good luck on your project.
MSS