Eddy heads - will I feel a difference on my 340 ?

I think I'll hold out and think this one through awhile. As said - motor is a 69 with original X's, supposed mild porting so maybe upping the port job would be more economical at this point (?). Goal was to build it the way I wanted it while it's out, not a big deal. Guess I'll go with the flat screen TV in stead of the Eddies! Anybody familiar with these guys: http://cgi.ebay.com/ebaymotors/Mopa...ryZ33617QQssPageNameZWDVWQQrdZ1QQcmdZViewItem