I had one of the first sets of Edelbrock heads in production so many of my observations may not still be true. Here goes,
First know up front that the swap requires aftermarket Head bolts,Longer hardened push rods, Special roller rockers and deeper valve covers.The exhaust bolt holes are not helicoiled and feel very shakey. also check the intake ports VERRY carefully. mine had water passages drilled into the intake ports on the four corners. After sorting out all that shit my Tahiti that ran 46 MPH before, now ran 69.6mph with the addition of the heads, a diverter, loading grate,added a Mondello jet cam and replaced the flywheel with a flex plate. It was like a totally different boat. I doubt that they could be duplicated with ported stock heads as the Edelbrock heads actually have rather small ports. If they got their crap together and you know the true cost up front I would say go for it. but plan on spending over 2K