I once had a Mercury KE4 or Mark 7 with a broken crankshaft and a powerhead
with a good crankshaft...in about a week of after supper work a complete
and running KE4 / Mark 7....without counting parts and valuing my labor
at $20 an hour that came out to roughly $400...a shop mechanic could
do the job much faster but also at a shop rate of about $100 per hour.
Even if you provide all the parts, shop manual and service tools the labor
and overhead costs make it impractical for a shop to work on antiques. Shops
already have enough orphan repair jobs owners abandoned.
That is why old outboards are cheap...the cost to repair/restore as a hobby is
mostly time not money IF the project is well chosen.