its been siting a long time. I am of the opposite opinion on the brake-in oil. I would use brake in oil because it has additives that are intended to almost super lubricate the parts enough to allow them to mate on initial run in without failing. Seems to me that something like that may be helpful to a motor that has been sitting for a while and may have some rough edges internally. With parts and machine work at such a premium these days, why not give yourself every edge to successfully start this motor and keep it running.
I have had very very good outcomes with the Brand Penn 30 wt. Brake in oil (now called Penn Grade 1 but its the same exact green Kendal ! oil its always been).
https://penngrade1.com/products/high-performance-oils/penngrade-1-break-in-oil-sae-30/
