I just wantd to drop you a note, to let you know you're in good company, running out there with Alan J ! Guess both of you guys share good taste in boats, eh?
In any case, if money was no object, most collectors would go with the original power as Mr. J did, (and as you have)! I see the same issues with vintage cars, the more valuable the boat or the car, the more important it is to have original power. On our larger Commanders, many have not reached the sort of collector status of smaller boats, and original power is not an issue. The 427 powered boats may become an increasing exception to this.
You are right, it's a hassle to go with original power, but I can assure you, many of those "convenient" repower projects are FAR from the simple task one might anticipate when they fork over the cash for a new powertrain. Many times there are clearance and motor mount issues, and in the end if you have a fresh CC SBC, the darn thing will still get into the 50-mph range and last just as long as a new one!!
I can get easily into the 50-mph range in my 17' Speedboat, but you don't want to be in it and hit a wake, because when you leave the water in that boat you're in trouble!

Not so in a 19 Commander Super Sport.
As for the price of one without a motor, it would certainly depend upon the condition. I wouldn't think twice about picking up a cheap 327 and spending the $1500 to $1800 it would take to make one last another 20 years. Finding a V-drive may be more difficult, but I'd sooner go with a new Vdrive than a new motor, because you can't readily tell wien you pop the hood.
With collector boats, as with collector cars, if you pop the hatch on a Chris Craft Cobra (or a Shelby Cobra) and you see something like a Honda Acura V8, it would be a bigtime turn-off for most boating enthusiasts who would have been drawn to the boat in the first place.
Someone please give me a ladder so I can get down off this soap box! (thanks in advance

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All the best,
Paul