What size Holley on there? I also had a Edelbrock intake plus a 650 holley......you really dont want too big a carb. it just blows fuel thru it..(on one of my earlier cars I changed down on carb size , got more power and better mileage..) the 7J2 heads are very unlikely fitted w larger valves, but you never know... they could be milled some , but if money was spent on them , they prob. should have done that on larger valve heads....maybe they also put other rockers in? to really know it seems you`d have to take heads off... But my guess is that they may just have put another cam in....can you ask former owner? then when you know, use that info to go forward w as you look at bigger valve heads...etc.
