Old Akro,
Been able to spare only a few minutes on this, and I am sorry but the last few weeks I have been very time challenged.....
If I was going to come up with a formula that might work, I would be aiming for 35-36" / 2450 or there abouts that is smooth, and around 40dF LOP which if my guessometrics are close enough should give you around 75% power on about 41-42 LPH.
If I get a chance to do this with the backward Aerostar, I will do a lower power say 26"/2450 GAMI lean test first to verify we have a conforming engine, and then give it a try. Some Turbo engines do not play as nice as others at higher MP.
If we can get some good data I am sure one of us will report back.
PS: I must confess that my Seneca experience is limited to teaching an experienced CFI how to hot start one.....(no, not kidding, I am serious)