Rebuilt engine - sitting on a shelf
 

I have the chance to buy a killer motor built by a reputable shop at a fair price. The engine was built, dyno'ed and tuned for a client that changed his mind. Meanwhile this beauty has been collecting dust; 4 years worth.

Is there anything special I should worry about?

As long as it's been inside and it spins you're OK !

And most certainly, DON'T start it dry without priming since you weren't there for assembly lube application. I'd oil cylinders and then hand rotate too. Good luck

You should worry about the connecting rod bearings - some of the Glycos were junk , the chain tensioners , Sebro timing chain sprockets - again some were junk and is the oil t-stat actually working to name a few things .

Worry about it more before trading cash for engine.

The seller should allow you to test the engine (compression, leakdown) and perform basic inspection to confirm their claimed condition. If you're not able, hire a local Porsche wrench to assist. The seller's reputation, if any, can be taken into account. Other than that, proceed methodically. Check related invoices and machine work. If he wants to sell, he should be willing to provide evidence to convince you. If not, that's more negotiating power for you. Any lack of cooperation and/or further evidence relegates this to a possible core status, then price it accordingly.

Once you have it, if you have other anxieties, go ahead and pull the heads, cylinders and rods and inspect, replace, repair and/or rebuild as needed.

Sherwood

Reputable shop means you don't need to worry, or take everything apart to inspect it. Get a warranty or something in way of assurance for your concerns, if you have any