You will need to do a longer phase 1-------40 vs. 25 hours if you do not have a certified engine and prop combination.
Chances are very good this will not come into play. The key word is "combination". If you take a TSO'ed engine and put a prop on it that was never used with that exact same model / sub-variant on a certified aircraft, then you get a 40 hour Phase 1.
Not to worry, save your money and go with the non-TSO'ed engine. Heck, after your TSO'ed engine is put in an experimental airplane, all bets are off.
Mel, do you want to chime in here?
Also, as I found out, the warranty on the experimental Lycoming is shorter than the certified engine. Read the owners manual to find out.