Original is good if you like original.

If you like the original look and don't mind some subtle improvements then a later model 235 or ideally a 261 is a very smart upgrade.

I expect you'll have more money in rebuilding the old 216 than it justifies, unless you appreciate and desire "original".
A 261 on the other hand will also cost something to rebuild (perhaps slightly less?) in the end you have a desirable engine, more power, slightly better with insert bearings and full pressure oil, even full flow filtered oil if you want.

The changes necessary to install the later 235 or 261 in your truck are small and well documented, in my opinion not a big deal or expense.

I would say spending money on "original" if that's not what you really desire would be wasted. Having been down that path myself; rebuilding a 235 before learning about the 261, in hind sight I would have liked the 261. If I had rebuilt an old 216 without understanding the later engine options I would really be kicking myself.
If for some reason you don't like the more modern stuff and want to go back to "original" that's still an option. The 235 or 261 doesn't require any cutting or anything that can't be easily undone.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-