So whats this kind of swap cost to do???

not to sure on all the details on the mega squirt,,, ive seen one,it was a kit had to be assembled like an old heath kit ham radio kit,,, or the cost,,,,but to go to a carb the intakes arent cheap,,but yes easier then a 3 gen hemi,,, but now almost impossible to find a low mileage magnum motor,,,so theres the rebuild cost also,,

The cheapest intake I saw was on ebay. $140 You can also have the magnum heads drilled and tapped to take a standard intake. I put a 6pack on my magnum headed stroker 318. Megasquirt ecms are available in kit form or assembled for around $350 Low milage magnums are rare today you are correct but you can buy a stock reman for around 1500-1700 bucks.