the problem with what you suggest sounds like what you want is $$ for a repower despite it actually being a decent option for someone not wanting to own a boat and its associated costs...
for example some might like the idea of partnering into a fresh repowered boat as they will think so as being more safe than an old ratty looking atomic 4 for example
the issue I see here is that you are asking for a partnership BEFORE the work has been done
my advice would be to scope out partnerships for engineless sailing at the moment if you get any bites tell them your plans but dont start off like with your first post here...
it will more than likely scare off any potential sailors since right or not it sounds like you want $$ for a repower and autopilot
here is a left field scenario
offer 50% of your boat by offering to co sign the title...provided that person helps you with the repower...if either wants out of the deal he she would have to no matter what get the other partner to agree...meaning that your partner is really an owner so it might be more worth it to him to invest right off the bat...
however from experience these scenarios rarely ever exist, especially in todays very cynic and un beleiving society where every single question or thought is considered a scam...
just my cents
ps. a mid line, good shape, sailable bahama with a good interrior but engineless in california for example could get anywhere from 4k to 8k depending on condition
as usual value is based on where you are, how good is your boat? and btw you dont mention what inboard you currently have
for example this guy is way overpriced at 28k even though it has all the goodies
where do you fit in here condition wise reallistically?