To find the value we would need to know more about what you are selling?
What is included with the block? is this just a bare block with main caps?
or is it a complete short block with rotating assembly?
Is it a long block complete with heads?
or a complete engine from carburetors to oil pan with all the original tins?
here is an example of the same year and size engine you say you have, that is currently for sale on eBay. it is listed for $3,000 with local pick up.
this does not really show its worth this is what this company is trying to sell it for.
This engine could sit on eBay for years and never sell at 3K
they could also relist it for 5K and sell it the same day if the right person comes around and absolutely has to have what they are selling.
Many people use the engine casting numbers when searching for a particular engine, if it is not mentioned in the title it may never get noticed same thing if they made a typo when creating the listing.
http://www.ebay.com/itm/1961-PONTIA...m231d820fdf:m:m1zjpT7bumt_o0N7osRpkSA&vxp=mtr
It appears to be somewhat complete yet not a numbers matching engine, the block has been repaired. and it looks like it would require a full overhaul.
It has 44 watchers and no recent history of the same engine being sold on eBay.
it is a desirable engine to have, but you have not clarified what your selling.
On an engine like this specific details are needed to make a determination of a value.
A block like yours that doesn't come with information like what is the current bore size for each cylinder or deck height, and other critical information is a gamble for the purchaser. they could spend hundreds of dollars in machine shop fees to find out they just purchased a 600 pound paper weight.
you say you had it tested, great what was tested and what is the details of this test.
A block that is at standard bore, has no cracks has the factory deck height and does not require extensive machining. will fetch more than one that is .060 over with a low deck height.
and obviously the more parts that are in or on the engine that came with it originally makes it even more valuable.
No one said anything about you screwing anyone over. I have just been trying to answer your question. but to do so you have to answer my questions.
I am all for you getting a fair price for this block, you have kept it safe and off the drag strip for many years. this alone has got to be worth paying for your efforts.
Help me help you by answering a few questions.
Without any of this information that you haven't provided,the only thing I can come up with is.
write down what you paid for it 20 years ago figure a reasonable inflation rate, add a reasonable amount for your labor that it took to find it buy it and move it to where it sat for 20 years after the testing you did, the price of the testing.
Add a fair amount for storage,up the price to where your comfortable selling it, because it is so rare. even include some money for the time you have to take out of your life selling it to this guy.