Well, replacing the plastic "deadeye and lanyard" assemblies on the Revell kit isn't, in itself, particularly time-consuming. I did it on the one I built way back in the seventies, as a matter of fact. I don't remember just how the parts representing the deadeyes and the channels are arranged, but the job amounts to slicing off the deadeyes and replacing them with wood or metal ones. A series of holes needs to be drilled where the old deadeyes were; the new ones can be held in place with wire or even thread. You might also want to think about replacing the chain plates, but they don't look bad if they're cleaned up carefully.
The tricky part of the process is rigging the genuine, thread deadeye lanyards. As I've mentioned several times in other Forum posts, I personally find that just about the most trying part of ship model rigging. In theory it's pretty simple, but getting the upper deadeyes lined up in a straight line and more-or-less uniform tension on the shrouds, without making the mast lean too much in some direction, is a challenge. I've seen various jigs and fixtures that people have devised in attempts to make it easier, but in my experience there's just no substitute for getting some practice. I frankly don't suggest a big ship, with lots of shrouds, as a first effort for rigging your own shrouds.
I remember, back when I was working in a hobby shop, examining a ad for what must have been that same Mantua kit. The brochure contained glorious color photos of the cast brass bow and stern ornaments. (The company also sold them separately - in a velvet-lined wood box.) It struck me that they looked remarkably like their counterparts in the Revell plastic kit. And the scale of the Mamoli version was 1/98. The Revell kit is on 1/96. Brass castings shrink by two percent as they cool. Hmmmm.
I had another curious experience with one of those European manufacturers. I went into a hobby shop that specialized in ship models (such establishments really did exist, once upon a time). The proprietor produced, with a considerable flourish, an item that had recently arrived: a pair of "bronzed metal" castings from (I think) Mamoli that supposedly represented the carved trailboards of the Cutty Sark. I don't remember the price of them, but it was considerable. Several other customers were admiring these things. I said I thought they were out of proportion and rather crude; that the Imai and Airfix plastic kits, and even the decal versions in the old Revell one, actually were better scale representations of the real thing. Everybody looked at me as though I'd either gone out of my mind or blasphemed.
The interesting thing about that conversation was the venue: Maritime Models of Greenwich. Everybody present had walked by the real Cutty Sark on the way to the shop.
Those continental European wood kits have a strange mystique about them that has little to do with scale modeling. If you do a Forum search on the word "HECEPOB" (that's Hideously Expensive Contintental European Plank On Bulkhead) you'll find several interesting discussions of the subject. Bottom line: if you're seriously interested in scale ship modeling, getting rid of that Mantua kit was an extremely smart thing to do.