Well . . .
I hope the owner likes the car a lot, because he's likely to have it a long time if he expects 30K for it.
One of the first rules of collector car values is that correct and original cars generally bring the most money, except in instances where the modifications are well known, documented, and appropriate to the car. An example would be an old BMW with Alpina speed equipment on it. They were BMW specialists 40 years ago with a good reputation for equipment that worked well with the car.
A set of Edelbrock high performance 6066 heads on a Lincoln is peculiar, and the seller seems clueless as to any particulars on the engine. Edelbrock does assemble crate engines, but in their current catalogue they are all based on Chevy small-blocks so it probably isn't an "Edelbrock 6066 engine". I'm guessing that the heads are on the original 460 block, which means low-compression pistons and a low-revving cam. If that's the case it probably runs just fine, as Lincoln intended, with maybe some extra oomph. If it is a real high performance, high compression engine with lots of overlap in the valve timing then it would have that classic loping idle and less than smooth exhaust note, especially with an automatic trans. That's all fine if it's in a muscle car, but in a Lincoln? I don't think so! The seller should at least research the engine and provide some documentation if he wants a high price for the car. Another issue is that engine, if it is far from stock, may not pass smog tests and in fact the test station may refuse to test it at all due to the non-stock air cleaner. This might be one reason the Lincoln seller wants to ebay it, in hopes of it leaving California for a place where it won't have to be tested.
Bongobro - I thought the Celebrity conversion was kind of strange, and I don't think I've seen another. My friend bought it as a collectible but he loved to buy and sell and so didn't hang onto it long. Nobody know the original owner, but I'd guess that it was a Chevy dealer who wanted a convertible other than a Corvette for his own personal use, because for the money any sane person would have ordered an Olds or Buick instead. Sure was a nice conversion.