Advice on re-powering 454 in a 268 Sundancer

My 454/Bravo II has 750 hours, 30+ years old, raw water cooled and recently started a rear main seal leak. With that I know I will have to remove the engine, so I thought for a "piece of mind" that I would just re-power her.
I am capable of doing the job myself, although I would have to buy or build a gantry/hoist.
My first question. I'm looking to hear from others if it is worth doing all this work myself or just pay someone to do it?
Which leads me to my second question. What and who am I looking for to do this job? I've looked on Craigslist and Marketplace for engines, and I'm not finding much. I'm not sure if that is a good resource, or is there something better? And I'm pondering if I should get a long block and change the accessory items myself, or look for a complete drop-in.
Any advice or stories would be greatly appreciated.

I had to replace one of my 5.7’s last year. I spent 3k total out of packer. Estimates ranged from 9-12k. I ordered a remanufactured 4 bolt main short block with brass plugs from Jegs, had the heads reconditioned and transferred the remains parts and accessories.

I just did a repower of my 1994 400EC using remanufactured long blocks. I purchased them from Promar Engines in Patterson, NJ. They shipped the new blocks to my boat. I removed both engines from the boat, disassembled them and transferred the parts to the new blocks. I took the opportunity to replace, reconfigure and upgrade some of the components while I was at it. (some pictures are in the 400EC Thread under Sport Yacht if you want to take a look)
From my research, since the 7.4 block is no longer made, a reman is your best bet. There was one company from Louisiana, I think, that still had NEW motors, but they were $11,500ish. If you can find a decent used 8.1 you could use that also as it is the same block.

PS you could also send your block to a reman shop to have them rebuild it.

The 8.1 is GM's bastard child, it's a metric motor and not the same as the 7.4 or 8.2

scoflaw said:

The 8.1 is GM's bastard child, it's a metric motor and not the same as the 7.4 or 8.2

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I knew one of them was the same block as the 7.4, guess I picked the wrong one