E7's are 64cc and not a clue on standard GT-40's. I suspect they're the same though. The GT-40P's were 60cc however. 4cc's won't bump compression but maybe a half point if you're lucky.
I don't know about that much HP at the wheels. Your gains are going to come from the intake and rockers, but you'll lose some because of compression. I think you'll maybe gain a few upper end HP, but not 25.
the stock E7's are anywhere from 59-61cc depending on factory tolerances. The stock Iron gt-40s are 64.5-66cc. I believe these are the right numbers. Stock compression is 9:1 and putting the gt-40 iron heads on there will most likely drop you a half a point.
As for your smoking problem. Whats the condition of the bottom end? Mileage? Compression and leakdown test results?
What about those gt-40 heads...were they brand new or used? What were the conditions of the valve guides and seals.
Are you sure you are burning fuel? or are you burning oil? Seems kind of unlikely for a stock)ish car to burn excess fuel at high rpm? Just some food for thought!